Hi Splinter,
The X-Plane 430 & 530 GPS are based on real-life Garmin models. Here is a series of video tutorials I found that might help you get started with it. They're both pretty similar, just the 530 is larger so the map is visible initially. On the 430 you have to click on the cockpit icon it to bring up the larger window, then use the smaller dial on the right to turn the Nav menu one to the right to see the map.