Don't worry, it's not as hard as it sounds but if you do it right, it's very rewarding.
Learn the basics of marketing. Build value, then sell.
You can check out my website (Internal Affairs) for a few blog posts on marketing, which should help you (there's a new one about targeting your market that I'll be posting tonight - sign up to the newsletter to be notified when it goes live).
Also, check out the marketing section of this forum. You may find a few helpful posts.