If you're able to install programs on the computer from which you want to be able to bypass firewall or Internet restrictions, you can install TeamViewer on both the current computer and your computer at home to be able to access your home computer's desktop. read more
For instance, let's say that your school blocks Facebook. In simplest terms, this is roughly what happens: Your firewall blocks Facebook; You go to the proxy - not Facebook. The proxy requests Facebook's homepage for itself, not you. The proxy's firewall isn't blocking Facebook. The proxy displays the content from its own website to you. read more
To get a better insight into how firewalls work, you can take this networking course. You might have to learn how to reconfigure your and network in general to get around a firewall that an IT department is overseeing. read more