Register for this website at the bottom left.
Click on Forums.
You can't post anything, save for in the introduction forum. (Category: Core General > Introduction Thread)
Make a new thread there and an admin will promote you and respond when you have been promoted.
Until then you can still peruse the other boards so you can get straight to posting as soon as you're registered, RIGHT?!

I will periodically promote people that I know have registered, but an introduction is still nice, not everyone knows who you are!