How do I sign up to use the guild forum?
Click the forums. Click a category. Click a thread. At the top of any thread is a white button labeled "Login or Signup". You can log in with almost any kind of account, Google, Facebook, Yahoo, Hotmail, AOL..... but you can also create a weebly account for logging in as well.
Can I post pictures to the forums?
Not as of yet, though it is something I'm looking into.