HTTPort allows you to bypass your HTTP proxy, which is blocking you from the Internet. With HTTPort you may use various Internet software from behind the proxy, ex. e-mail, instant messengers, P2P file sharing, ICQ, News, FTP, IRC, etc.
The basic idea is that you set up your Internet software in such a manner, that it connects to your own local PC as if it was the remote server it needed. HTTPort then intercepts that connection and runs it through a tunnel through the proxy.