I'm seventeen and I'm writing a Forum - but seriously age doesn't matter.
If you're able at 13, do it, if you're able at 15, do it - Advertisements are always evil; but some people decide to do them and its their calling - you people don't like ads don't go on sites with them.
Nice forum though - always a fan proboards users. It means when I make up a Multi-Free Forum Software and can just search through here for Proboards and get a huge list of people to offer it to.
A Knight is sworn to Honour. His heart knows only Virtue. His blade defends the helpless. His might upholds the Weak. His word speaks only truth. His wrath undoes the Wicked.