How to use pointers in my coding?

#include <stdio.h>
#include <stdlib.h>
#include<math.h>
#include<string.h>
#define name 20


struct detail
{
    int iway;
    int oneway;
    int twoway;
    int age;
    int id;
    int id2;
    char cname[name];
    char date[10];
    char date1[10];
    char itime[10];
    char itime2[10];
};

struct place
{
    int idestination;
    char jb[30];
    char pen[30];
    char ter[30];
    char lg[30];
};

void main()
{
    void booking(),check(),display(),cancel(),save();
    struct detail sdetail;
    struct place splace;
    char user,pass;
    char choice;

          printf("Enter username: ");
          scanf(" %s",&user);
          printf("\nEnter password:");
          scanf(" %s",&pass);
          system("cls");
	do
	{

		printf("\n\n\t\t ********************************************************************");
		printf("\n\t\t                  WELCOME TO DINS AIRLINES                            ");
		printf("\n\t\t   *******************************************************************");
		printf("\n\n\n\t\t Please enter your choice from below (1-5):");
		printf("\n\n\t\t 1. Booking");
		printf("\n\n\t\t 2. Check Schedule");
		printf("\n\n\t\t 3. DISPLAY RECORDS");
		printf("\n\n\t\t 4. Cancel");
		printf("\n\n\t\t 5. EXIT");
		printf("\n\n\t\t Enter your choose ");


		scanf("%d", &choice); fflush(stdin);
		system("cls");  //(cls" is a command on some operating systems that clears the screen

		switch (choice) // (Each value is called a case, and the variable being switched on is checked for each switch case)
		{
		case 1:
			booking();
            break;
		case 2:
			check();
			break;
		case 3:
			display();
			break;
        case 4:
            cancel();
            break;
		case 5:
		{
				  save();
				  break;
		}
		Default:
			printf("\n\n\t SORRY INVALID CHOICE!");
			printf("\n\n\t PLEASE CHOOSE FROM 1-5");
		}
		getch();

	} while (choice != 5);
}

void booking()
{
    struct detail sdetail;
    struct place splace;
    char user,pass,key;
    int choose,ticket;
    char proceed,choice,meals;
    int c,p,a,sum=0;
	int i;
	int j;
	int s[40]={};
    float pay=0,total_price;


        printf("1.KL - JOHOR BHARU\t\t\t\t 0830-0930\t 1400-1500\n");
        printf("2.KL - PENANG\t\t\t\t\t 0800-0900\t 1300-1400 \n");
        printf("3.KL - TERENGGANU\t\t\t\t 1000-1120\t 1700-1820 \n");
        printf("4.KL - LANGKAWI \t\t\t\t 0900-1015\t 1600-1715 ");

        printf("\nHow many ticket did you want? ");
        scanf("%d",&ticket);

        for(a=1;a<=ticket;a++){


        printf("\n---------------------BOOKING TICKET----------------------\n");
        printf("NAME: ");
        scanf(" %s",&sdetail.cname);
        strupr(sdetail.cname);
        printf("AGE: ");
        scanf(" %d",&sdetail.age);
        printf("PASSPORT ID: ");
        scanf(" %d",&sdetail.id);
        printf("\nCHOOSE YOUR DESTINATION: ");
        scanf(" %d",&splace.idestination);


    if(splace.idestination==1)
    {
        splace.idestination==splace.jb;
        //printf("KL - JOHOR BHARU");
    }
    else if(splace.idestination==2)
    {
        splace.idestination==splace.pen;
       // printf("KL - PENANG");
    }
    else if(splace.idestination==3)
    {
        splace.idestination==splace.ter;
       // printf("KL - TERENGGANU");
    }
    else if(splace.idestination==4)
    {
        splace.idestination==splace.lg;
       // printf("KL - LANGKAWI");
    }
     printf("\nCHOOSE YOUR WAY(1-ONE WAY,2-TWO WAY) :");
    scanf(" %d",&sdetail.iway);


    if (sdetail.iway==1)
    {
        sdetail.iway=sdetail.oneway;
         printf("\nDeparture date:");
        scanf(" %s",&sdetail.date);
        printf("\nDeparture TIME: ");
        scanf(" %s",&sdetail.itime);


                    if(splace.idestination == 1){
                        pay=130*1;
                        }
                else if(splace.idestination == 2){
                         pay=150*1;
                        }

                else if(splace.idestination == 3){
                         pay=170*1;
                        }

                else if(splace.idestination == 4){
                         pay=200*1;
                        }
    }
    else if(sdetail.iway==2)
    {
          sdetail.iway=sdetail.twoway;
          printf("\nDeparture date:");
          scanf(" %s",&sdetail.date);
          printf("\nDeparture TIME: ");
          scanf(" %s",&sdetail.itime);
          printf("\nReturn date:");
          scanf(" %s",&sdetail.date1);
          printf("\nReturn TIME: ");
          scanf(" %s",&sdetail.itime2);


                    if(splace.idestination == 1){
                         pay=130*2;
                        }

                else if(splace.idestination == 2){
                         pay=150*2;
                        }

                else if(splace.idestination == 3){
                         pay=170*2;

                        }

                else if(splace.idestination == 4){
                         pay=300*2;
                        }

    }
    else
    {
        printf("INVALID\n");
    }
    for (j=0; j<1; j++)
	{
		printf("\nChoose 1 for First Class and 2 for Economic class\t");
		scanf("%i",&c);

		switch(c)
		{
		case 1:
			printf("\nFirst class\n");
			printf("Seats available are 1-10.\n");

                printf("Pick a seat:\n\n");
                scanf("%i",&p);
                sum=100;
                s[j]=p;

			    for (i=0; i<j; i++)
			    {
                    if (s[j]==s[i])
                    {
                        printf("\n\nSeat taken.\n\n");
                        break;
                    }
			    }

            break;
		case 2:
			printf("\nEconomical class\n");
			printf("Seats available are 11-30.\n");

                printf("Pick a seat:\n\n");
                scanf("%i",&p);
                sum=50;
                s[j]=p;

			    for (i=0; i<j; i++)
			    {
                    if (s[j]==s[i])
                    {
                        printf("\n\nSeat taken.\n\n");
                        break;
                    }
			    }

            break;
        default:
                break;

		}
	}

	   printf("\nCHOOSE YOUR FREE MEAL :");
	   scanf(" %s",&meals);

	   switch(meals)
	    {
        case'A':
            printf("KFC");
            break;
        case'B':
            printf("MCD");
            break;
        case'C':
            printf("DOMINOS");
            break;
        default :
            break;

	    }

	     total_price=(pay+sum)*ticket;
}
}
void check()
{
        printf("1.KL - JOHOR BHARU\t\t\t\t 0830-0930\t 1400-1500\n");
        printf("2.KL - PENANG\t\t\t\t\t 0800-0900\t 1300-1400 \n");
        printf("3.KL - TERENGGANU\t\t\t\t 1000-1120\t 1700-1820 \n");
        printf("4.KL - LANGKAWI \t\t\t\t 0900-1015\t 1600-1715 ");
        return;
}
void display()
{

    struct detail sdetail;
    struct place splace;
    int p;


      system("cls");

       printf("\n===============================================================\n");
       printf("NAME : %s\n",sdetail.cname);
       printf("AGE : %d\n",sdetail.age);
       printf("PASSPORT ID : %d\n",sdetail.id);

        if(splace.idestination == 1){
                strcpy(splace.jb,"KL-JOHOR BHARU");
                printf("DESTINATION : %s\n",splace.jb);
                        }
         else if(splace.idestination == 2){
                strcpy(splace.pen,"KL-PENANG");
                printf("DESTINATION : %s\n",splace.pen);
                        }
            else if(splace.idestination == 3){
                strcpy(splace.ter,"KL-TERENGGANU");
                printf("DESTINATION : %s\n",splace.ter);
                        }
        else if(splace.idestination == 4){
                strcpy(splace.lg,"KL-LANGKAWI");
                printf("DESTINATION : %s\n",splace.lg);
                        }

       printf("SEAT : %d\n",p);
       printf("DEPARTURE DATE: %s\n",sdetail.date);
       printf("DEPARTURE TIME: %s\n",sdetail.itime);
       printf("RETURN DATE: %s\n",sdetail.date1);
       printf("RETUN TIME: %s\n",sdetail.itime2);
       printf("\n===============================================================\n");


       printf("\nPlease pay your ticket using online banking or master card.");
       printf("\nThank you for choosing our airlines.Enjoy your holiday!");
       return;
}

void cancel()
{
    struct detail sdetail;

    printf("Enter your PASSPORT ID: ");
    scanf("%d",sdetail.id2);

    if(sdetail.id2==sdetail.id)
    {
    printf("\nYour cancellation is successful.");
    }
    else
    {
        printf("\nYour cancellation is not successful.Sorry!");
    }
    return;

}

void save()
{
    float total_price;
    printf("TOTAL OVERALL : RM %.2f",total_price);
    printf("\nPlease pay your ticket using online banking or master card.");
    printf("\nThank you for choosing our airlines.Enjoy your holiday!");
    return;
}