Two programs i like to use to get around firewalls xD
TOR: The Onion Router. A project started by the US naval research laboratory to get around foreign firewalls for research purposes. It uses the onion routing method to make transmissions anonymous and very difficult to trace. (Overkill for a school firewall)
TAILS: A bootable operating system using the Linux base that uses only a computer's RAM to run, leaves no trace, and allows you to get around just about any firewall. (Complete overkill, like slicing a melon with a nuke, against a school firewall)
I think both are now maintained by the EFF, so its free to use.
Oh, and both are quite user friendly.