Program using loops that gets minimum and largest numbers entered by the user

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C#

Hi! I'm trying to understand loops and I'm using this book. There's a question in it that I can't seem to figure out.
It's asking for a program with a loop that lets the user enter a series of numbers. After all the numbers have been entered, the program should display the largest and the smallest number entered. The user should enter -99 to signal the end of the series.

I can't figure out the main loop that will give me the minimum and the maximum value of the series.

Here's what I have right now:

EDIT 1: I changed the code and now I can get the user to enter numbers till they enter -99. Now I just need the loop that will give me the max and min values of the series.
Hope this is easier to read!

EDIT 2: I changed the code again. I figured out pretty much everything (thanks to all the suggestions!) and have this now. The code is running, but for the answer I get only 0 for some reason, not any number in the series. Is there a reason that this is happening? I think it has something to do with the parameters but I'm not sure.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Project_1
	{
	class Program
		{
		static void Main(string[] args)
			{//start main
			
			int number = 0;
			int min = 0;
			int max = 0;
			
			//start calling modules
			calculateMinMax(ref min, ref max, ref number);
			getInput(ref number);
		  display (min, max, number);
			//end calling modules
			 
			
			Console.ReadKey(); //keep program running
			}//end main	
				
	
	//start CalculateMinMax
			static void calculateMinMax ( ref int min, ref int max, ref int number)
			{
			if (min == 0 && max == 0)
				{
				min = number;
				max = number;
				}

			if (number < min)
				{
				min = number;
				}

			if (number > max)
				{
				max = number;
				}

			}//end calculateMinMax

	//start getInput
			static void getInput(ref int number)
				{
				while (number != -99)
					{
					Console.WriteLine("Please enter the numbers in the series. Enter '-99' to end the series.");
					while (!int.TryParse(Console.ReadLine(), out number))
						Console.WriteLine("Error. Please enter a number.");
					}
				}//end getInput
			
			
	//start display
			static void display (int min, int max, int number)
			{
			Console.WriteLine("The largest number in the series you entered is {0}, and the smallest number in the series you entered is {1}.", max, min);
			}//end display

	

			}//end class
		}//end program

Any help will be appreciated! Thanks! :)