If you're still looking for help on this, you could use a proxy that runs through another persons ISP.
Peacefire.org is the homepage, and their latest circumventor is starclapper.com
It might still be blocked, because your school's security could just be blocking all https (yes, https, it sounds dumb, but it's real. Secure Http? my ass.) sites.
If that's the case, and you don't mind mind-blowingly slow internet, you could use torpark.
But I've seen a school block that too...
If worst comes to worst, try making friends with the Sysadmins.
They might have a connection outside of the hardware firewall, without the block on it.
Or, you could find that connection, depending on how they have it secured on the network, and run an ethernet cord from it.
But that would be really hard, and good for about 2 minutes. Just, never admit defeat, becuase then those traitors have won!