A proxy isn't something you install on your computer -- it's a server that you go through to get to another server. Your IP address is something that's assigned to your computer when you connect to the network, and as long as your requests are coming directly from your internet service provider, it's going to have a "poison" IP address. You need to go indirectly -- you make a request to a server in a different country, and it makes a request on your behalf using its own IP address (one that isn't banned), then sends the response it gets to you.
You will often see these services listed as "anonymizers". A word of warning here -- not all free proxy server (or free anonymizers) play nice. They're often a way to gather your personal data (usernames, passwords, email accounts, and so on) while making you feel happy about it. Before you decide to use a proxy service, do a bit of investigation to see if it might be a scam in a fancy package.
