Implement Session And Retrieve From Mysql Table?

How do I implement this session: (UserID is part of the login table)

Session["UserID"]="usrName";
Into this code?
using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.Odbc;
using System.Data.SqlClient;
public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Login1.Authenticate += Login1_Authenticate;
}
protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
{
//database connection string
OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite; User=x; Password=x; OPTION=3;");
cn.Open();
OdbcCommand cmd = new OdbcCommand("Select * from User where username=? and password=?", cn);
//Select the username and password from mysql database in login table
cmd.Parameters.Add("@username", OdbcType.VarChar);
cmd.Parameters["@username"].Value = this.Login1.UserName;
cmd.Parameters.Add("@password", OdbcType.VarChar);
cmd.Parameters["@password"].Value = this.Login1.Password;
//use asp login control to check username and password
cmd.Parameters.Add(new OdbcCommand("@UserID", 'id.int'));
OdbcDataReader dr = default(OdbcDataReader);
// Initialise a reader to read the rows from the login table.
// If row exists, the login is successful
dr = cmd.ExecuteReader();
int id = cmd.Parameters["@UserID"].Value;
Session["UserID"]="usrName";
if (dr.Read())
{
e.Authenticated = true;
Response.Redirect("UserProfileWall.aspx");
// Event Authenticate is true forward to user profile
}
}
}

I need to be able to retrieve the correct UserID when some one inputs there username and password upon login and then some how retrieve it on a new page something like this to retireve it but unsure?

string usrName = Convert.ToString(Session["UserID"]);

I just dont know how to add the first part, the session into my login code so I can some how store the UserID in my session but also retrieve the correct UserID from the submitted data that takes from my mysql login table.