l used to download movies,softwares and music videos using our school's wifi network connection,since we've paid for it.Now the network doesn't allow downloading anymore.lt only allows us to browse.what can l do in order to download files again?

If its against their policy, then you should abide by it and download those types of files at home. Getting around those rules by using a VPN server, or by accessing an open proxy may be a violation of their acceptable use policy so you should find out what the consequences are before you try to get around the system.

As JorgeM said, however you should be able to create a VPN (virtual private network) tunnel to an external service, and download that way. If you have to ask how to do that, I can only say that "Google is your friend"... :-)