For a good tutorial on skinning follow this link:
http://bsplayer.com/en/bs.player/ski...documentation/
If you plan to build BSplayer v1-like skins, u can use my skin maker (link in my sign or on BSplayer skin page). I suggest you to use it if you plan to edit already made skins... (it's explained also in the SkinMaker user guide the way in which BSplayer handles button's actions)