You do not need to be using any of these clauses of keywords to access the values of session variables. Just use this,
var val = Session["x"];
But since the variable might not exist, instead of above code, use the following to ignore any runtime errors,
if(Session["x"] != null) {
var val = Session["x"];
}
Now val would have the value set in the Session variable for x. You can use these variable in any page on the application, they exist throughout the session.