cgi redirection

Hello all. I'm new to PHP, but web dev. is my forte... In PHP how does one: do a CGI re-direction? For example. I have a user authentication script that checks against user name and password. Such a setup is in a classic format: login page submits to query page that checks agains member DB. I then want to load in a "web landing page" if the login is good, otherwise load in a "error logging in" page if the login is bad. The ideal way to do this is to "re-direct" the web server to either the landing page or error page - meaning the desired page is what the browser sees. On the other hand, my above thinking might be good in other languages but not for PHP??? Should I be thinking to include different files based on login success, instead of redirecting? Please help! -f