The easiest way to get access to Myspace at school is to use a proxy website. You can get on any site that is blocked by using this method. You can use the proxy here.
A proxy is a kind of gateway that passes information between your computer and the site you want to go to. The proxy goes to the site you want instead of you, loads the page, and sends it on to you. So the site you want to access never sees your IP. So in effect you are surfing sites in an indirect way. School firewalls only see you accessing the proxy, not the site you actually want.
It's best to find a proxy site that very few people know about. Popular proxies will get blocked faster. Proxies that you find by searching Google will get blocked more quickly because teachers can find them so easily. Even if you find a good one it's always wise to have an alternative you can use if it gets blocked.
An alternative method of unblocking Myspace in school is by making your own proxy tool. This is more advanced than using someone else's proxy but it's a lot nicer to have because you can make more of them. Here are some instructions: How to make your own school proxy. You can even earn money from letting people use it if you put ads on it.
Researchers have found that commercial filtering technologies mistakenly block access to content related to women’s health, gay and lesbian rights groups, and sexual education for teenagers. Everyone's Guide to By-Passing Internet Censorship for Citizens Worldwide