Yangshuo has two bus stations, the creatively named North and South bus stations.
All long distance buses will stop at one of these two stations. There are usually taxis hanging around to take you wherever you want.
If you just need to go into Yangshuo's downtown, then local bus #5 connects both bus stations and it goes past West Street. The cost of this bus is 1 Yuan per person. Just deposit the 1 Yuan into the money box as you board the bus