There are lots of different door stops on the market. Some serve just to keep the door handle from going through the wall. Others have clamps or magnets on them to keep the door open, especially when the wind tends to slam it shut. I really like the one in the photo because of its round shape, it lines up so easily, and really holds the door against those summer breezes.
The trick to installing these stops when they have two parts, is to install one side on the floor, wall or door. Attach the second part to the first and then open the door on it. Some of them actually have pointed markers built in. If not you can put slightly oversized screws into the holes to that they barely stick out, just enough to mark exactly where the piece should be screwed in.
All of the door stops shown were picked up at regular hardware stores.