Nice job for a first go. It's not too complex, but is still pretty interesting. 🙂
The only thing I'm not sure about is the actual 'theme' of it. The banner is the first thing people see on your forum and it should somehow express what will it is about. Your graphic looks nice, but it doesn't convey any meaning.
Have a think about who is 'looking' at your banner. If it's new members, make one that new members will like and that will tell them what your forum is about.
-lightened the grid
-changed the color of the people to gray
-added some more paint
-added question marks
-changed "forums" to white
What do you think? Is there just too much "stuff"? I want to make sure it's good before I put it up because my color scheme of Said Wicked depends on this banner.
Oh wow, very nice banner.
Only constructivism criticism I'll say is to make it either blend seamlessly with the board's background color or have it fill the entire gray background area.