Mike, most all slides are the same. With the slide extended, look under the outer edge. Usually there are vertical bolts that are double nutted that adjust the height of the slide. You'll typically have one at both ends.
Make sure the coach is sitting on level ground. Loosen the double nuts and adjust the bolt, lifting the slide. Make your adjustment and then retract the slide to see if the stripes line up, repeat procedure if necessary.
Often, if the slide has dropped a little, it can be rubbing on the opening casing your creaking noise. It's good idea to always check all of the components for anything unusual, broken welds or loose bolts. Once dune, lube the slide out mechanism.