Those are the results for The Gateway Open that was held in May 2014. The Pro, Masters, and Advanced divisions played Wilmore first, so take a look at the first two rounds for those specific divisions. All other divisions played Wilmore Sunday, so look at rounds 3 and 4 for those divisions. Also, I know the course has changed a bit, but I am not sure when those changes occured.
In a typcial PDGA tournament, usually the courses are set up a little longer than usual, additional OB can be added, and there is always that added pressure. From what I can see, if you can maintain an average of 57 out there, playing Advanced (MA1) seems appropriate, especially for a non PDGA sponsored event. If you have never played in a tournament before, playing Intermediate (MA2) may also be appropriate, especially for a PDGA sponsored event.
Showing up at a couple leagues and familiarizing yourself with the local players should also help gauge what division you should play. The individuals that run the area leagues do a TERRIFIC job and they are certainly always there to help! Check out the Events Reminder topic under the Tournaments and Events forum to find information about upcoming events and information about the area leagues.
Hope this helps out!