Lets take it as you have a role on your database as A(admin) U(user)
Use below code to check the role and redirect to their desired page
string Utype;
Utype = dt.Rows[0][10].ToString().Trim();
if (Utype == "U")
{
Session["Username"] = UserName.Text;
Response.Redirect("UserHome.aspx");
}
else if (Utype == "A")
Session["Username"] = UserName.Text;
Response.Redirect("~/Admin/Admin_Home.aspx");
}
else
{
lblError.ForeColor = Color.Red;
lblError.Text = "Invalid Username or Password";
}
}