Not to dampen your spirits, but it is highly unlikely you will be able to score access to your school's network.
Not only do they take time to set up users with passwords and proxies for their connection, they also take time to secure their networks with passwords.
Even if you do get on, most of the content you would want would probably be filtered.
Not to mention, it's probably against the usage policy of your school to have unauthorized device connected to the school's network.
Regards.