Maybe someone has answered this for you already, in which case, never mind.

Scroll down on the main Forums page and you'll see "Advertise Your Services". It looks like you can put a single post in there for free if you have an upgraded membership.

Scroll farther down and you'll see "Show Groups", which has a list of moderators. Contact one of them, and they should be able to put you in touch with the commercial advertising people.