Trying to use school's wireless...

I'm trying to use the wireless internet on my iPhone in my business hall at my school...and I've read online I need to set up VPN with PPTP or something like that to do it...under VPN on the iPhone I choose PPTP, put in my server, my name and password, set encryption to "None" and set "Proxy" to off. There is no instruction on my school website on how to do it on iPhone, only on windows mobile or palm. I pieced together what to do from those instructions, but when I try to connect on the iPhone I get the message "could not negotiate a connection with the remote PPP server. Please verify your settings and try again." Can anyone help me?