I do not have experience with your model, but I'd presume that there is some type of fastener that is meant for easy removal (knob-like) that affixes the bulb to the fixture. If you can see the back of the fixture, experiment and observe how the bulb is held on. If the ballast is attached to the back of the fixture (blocking your path to the bulb), you may have to remove the entire fixture, with ballast. Remember that if you are doing this yourself USE CLEAN RUBBER GLOVES TO HANDLE THE BULBS!!! HID lights, like halogens, Hg, or Na vapor bulbs, get really hot. The oils from your skin will get onto the bulb lens and absorb light and convert it to heat thus reshattering your bulb you just repalced where you touched it. This may have been the case if your bulb had been replaced before (perhaps by someone not as carefull as we'd like).
Also, if you end up having to remove the entire fixture, you can always take it to a shop to have the ballast tested. Or if you can, you can try swapping bulbs with the bulb on the working side of your car. If, by testing you discover the working bulb does not work in your other socket (the questioned side), you either have a poor connection (unlikely in a 98') or a damaged ballast (also unlikely).
Worst case senario, you need a new ballast and you have an extra bulb.