Need help with passing userid/session("userid") on login page

 I am trying to create a login page in C# and want to pass the userid(if it is even necessary) from SQL database through to the next page(reports.aspx) so it knows what user is logged in. The code I have is not working and I am having trouble doing this and need assistance.  Here is my current code, what do I need?

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

namespace HSI

{

public partial class login : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

Session["UserId"] = userid;

}

private bool AuthenticateUser(string uname, string password)

{

bool bflag = false;

string connString = "Server=portalsql;Database=portal;Integrated Security=True";

string strSQL = "select * from  icc_users where username ='" + uname + "' AND password ='" + password + "' and userid = '" + Session["UserId"] + "'";

DataSet userDS = new DataSet();

SqlConnection m_conn;

SqlDataAdapter m_dataAdapter;

SqlCommand m_Command;

try

{

m_conn = new SqlConnection(connString);

m_conn.Open();

m_dataAdapter = new SqlDataAdapter(strSQL, m_conn);

m_dataAdapter.Fill(userDS);

m_conn.Close();

}

catch (Exception ex)

{

userDS = null;

}

if (userDS != null)

{

if(userDS.Tables[0].Rows.Count > 0)

bflag = true;

}

return bflag;

}

protected void Login1_Authenticate1(object sender, AuthenticateEventArgs e)

{

try

{

string uname = Login1.UserName.Trim(); //Get the username from the control

string password = Login1.Password.Trim(); //get the Password from the control

bool flag = AuthenticateUser(uname, password);

if (flag == true)

{

e.Authenticated = true;

Login1.DestinationPageUrl = "reports.aspx?page='" + Session["UserId"] + "'";

}

else

e.Authenticated = false;

}

catch (Exception)

{

e.Authenticated = false;

}

}

}

}