Using Navigation like prev,next,save record in front end application connecting through northwind in dotnetcode

<div style="margin-removed 480px">
        <asp:Label ID="Label1" runat="server" Text="First Name"></asp:Label>
    
            
        <asp:TextBox ID="txtfname" runat="server"></asp:TextBox>
                
        <br />
        <asp:Label ID="Label2" runat="server" Text="Last Name"></asp:Label>
    
            
        <asp:TextBox ID="txtlname" runat="server"></asp:TextBox>
 <br />
        <asp:Label ID="Label3" runat="server" Text="EmpId"></asp:Label>
    
                  
        <asp:TextBox ID="txtempid" runat="server"></asp:TextBox>
        <br />
        <asp:Label ID="Label4" runat="server" Text="D O B"></asp:Label>
    
                  
        <asp:TextBox ID="txtdob" runat="server"></asp:TextBox>
        <br />
        <br />
        <br />
        <asp:Button ID="btnprev" runat="server" onclick="btnprev_Click" 
            Text="<< Prev" />
         
        <asp:Button ID="btnsave" runat="server" onclick="btnsave_Click" Text="Save" />
                 
        <asp:Button ID="btnnext" runat="server" onclick="btnnext_Click" 
            Text="Next >>" />
        <br />
        <br />
        <asp:Label ID="lblmsg" runat="server" Text=""></asp:Label>
    
    </div>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;

public partial class _Default : System.Web.UI.Page
{
    DataTable dt;
    int i = 0;
    public void print()
    {
        DataRow dr = dt.Rows[i];
        txtfname.Text = dr[0].ToString();
        txtlname.Text = dr[1].ToString();
        txtempid.Text = dr[2].ToString();
        txtdob.Text = dr[3].ToString();
    
    
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        
     
     }
    protected void btnsave_Click(object sender, EventArgs e)
    {

        string connStr = WebConfigurationManager.ConnectionStrings["master"].ConnectionString;
       
        SqlConnection conn = new SqlConnection(connStr);
        conn.Open();
        SqlCommand cmd = new SqlCommand("insert into employee values('" + txtfname.Text + "','" + txtlname.Text + "','" + txtempid.Text + "','" + txtdob.Text + "')", conn);
        cmd.ExecuteNonQuery();
        conn.Close();
        lblmsg.Text = "Successfully Registered";

        
        

    }
    protected void btnprev_Click(object sender, EventArgs e)
    {
        i = 0;
        print();
    }
    protected void btnnext_Click(object sender, EventArgs e)
    {
        i = dt.Rows.Count - 1;
        print();

    }
}

<configuration>

	<connectionstrings>
		<add name="Northwind"
       connectionString="Data Source=JAGADEESHWAR;Initial Catalog=master;Integrated Security=True"
      providerName="System.Data.SqlClient"/>
	</connectionstrings>
	<system.web>
		<compilation debug="true" targetFramework="4.0"/>
		
	</system.web>
</configuration>