You do have gold account, since you've bought the game on steam. I believe you created this account after that. You can get your gold account from the game, there should be "setup email for this account" (or something like this) button, Click it, if you haven't already. If you already linked your mail, then all you have to do is just login to forums, with user and pass you use in-game. If there are any problems, maybe we could discuss it privately?