How Do I Check Proxies?

Hi,
I just don't understand proxies at all and they rarely ever work for me. If I have a list of proxies how do I check if they work? I tried to use Charon but it didn't work. It says that I have a "Bad Judge" or something like that. Sorry for the noob question. I just really need help. So basically, what is the best way to check proxies?

Thanks