how to get online/offline mode Users in UserTable

1)CReate a login screen which will validate user with user name and password.
If he is valid user(obviously u check that in button Click) then create a session variable like
Session["UserId"]
2)Next create a MAsterPage and derive all your pages from that master page except login page.
3)On Page Load of MasterPage write folllowing Code
if(Session["UserId"]==null)
{
        Response.Redirect("Login,aspx");
}
4)Add a logout button in master page (or any where else)
and on Logout_clic write
Session.abandon();
        Response.Redirect("Login,aspx");


Check this is correct answer if it helped.