I would recommend anchoring upstream to begin with. While on the water, you can get a pretty good idea of what wings hold fish by watching where other boats are working regularly. Some wings that don’t get worked very much do hold from time to time also though.
Current, river level, temp, and several other factors all contribute to what dams and areas of the dam hold fish. It is great fun learning though, and you will be able to get lots of help here to shorten the learning curve!
I like to anchor above a wingdam, cast cranks to the top, pitch jigs to the top and face, and cast live bait rigs as well. There are many good ways to catch fish on wingdams.
One of my favorites is to “slip” across the face of the dam with my trolling motor, using a 3-way rig with a big jig for the drop weight, and a 3-6′ leader to a crawler on a hook, with or without a floating jig head. This technique takes a lot of practice and patience, but is very effective once you get the hang of it. Just be careful to tilt your outboard out of the water on shallow dams!
Good luck, let us know how things are going!