There are lots of resources available online to help you set up a website for your event.
Whether it be a Livejournal community, Myspace, Facebook, Wordpress, Ning or a more professional site, you need a place your potential attendees can easily find information specific to your event, a place to set up ticket/merchandise sales if they aren't handled on the day/by your venue. It's also an easy way to point media to your own event.
Once you have set it up keep it up to date! Even if you don’t have a lot of new information to share, just adding a short note on a regular basis will encourage people to keep checking for when you do have important information to share. Add information, photos etc on previous events to give new people an idea of what goes on.
The Global Team can help you if you need hosting, and you can also get your event listed with the CSTS domain - ie. http://www.cantstoptheserenity.com/youreventlocation