Step 1: Make Them, Hang Them, & Add Speaker
If at all possible, screw the top of the wall side bracket into a stud. If you hit wood, one screw will do it as long as it goes at least 1" into the wood (not including thickness of drywall or plaster). Don't screw it down so tight that the bracket digs into the wall, just snug against the surface. If you don't hit wood, then use any of the many types of drywall anchors that expand behind the drywall. I'd avoid the plug type, since they can pull out on impact in this application. Use a second anchor in one of the lower holes if you feel the need for extra strength or fear swinging speakers. In my picture, the shelf is mounted to brick. Plug anchors (like the conical plastic ones that come with everything) are fine for masonry.
FYI: If you mess up and trash your speakers I'm not responsible, period. As with anything and everything else, please use common sense, and get advice/help if you think you need it.