When you are successfully logged in then store required data in Session like this before you redirect to new page
Session["FullName"]=
Session[UserId]=
Response.Redirect("NewPage.aspx");
In newpage or any other page you can get this session back
if(Session["FullName"]!=null)
{
string name= Session["FullName"].ToString();
int UserID= Convert.ToInt32(Session["UserId"].ToString());
}