how do I get past the proxys at school?
You don't. They are there for a reason. To keep the schools network safe and to keep underage students from websites they shouldn't be on. Trying to "get past them" can only get you in trouble and make it harder for other students to go online to get the information that they need.
If you still need to get by them I would suggest you ask one of the schools administrators or the computer science instructor to help you out. But my guess is that you're trying to do something you know is wrong. So do yourself a favor and don't do it.
You are aware that by passing the proxy at some schools can get you kicked out for the year in some States. PLUS it is considered hacking which is a crime and can help you get an arrest record making it harder to get in some of the better colleges.