to show the logged in users name, you need to edit the authenticate user server behavior on the login page to have it store the name in a session variable.
on the login page, open the server behaviors panel and double click the authenticate user server behavior.
On the Sessions tab, Click the plus button and select the name column to have the name stored in a session.
on the page, where you want to show the name, go to the bindings panel expand the session collection and drag the User name session to the page.