How can I remain completely anonymous online?
You can’t be completely anonymous online. At a minimum, you leave little traces in log files every time you access something. Even registering and posting on Yahoo Answers could be traced if there was enough of a reason to do it. If you went to enough trouble, you could make it almost impossible for anyone to trace you, but it would only take a small slip to ruin that. It would take a lot of work to make it difficult for anyone to trace you. It would never be impossible. The best advice is don’t do anything illegal and mostly no one will bother you. The spammers will find you no matter what you do.