go to events of login control and add event
LoggedIn
, in the event code you could done something like below
protected void Login1_LoggedIn(object sender, EventArgs e)
{
if (Roles.IsUserInRole(Login1.UserName, "Admin"))
Response.Redirect("~/Admin.aspx");
else if (Roles.IsUserInRole(Login1.UserName, "User"))
Response.Redirect("~/Normal.aspx");
}