There are many different ways you can attach the pad so you can use it. If you are handy with the button hole feature on your machine, you could use that. Or you could hand sew a button hole and button if you like. Other people use ties. I think most people use snaps or Velcro.

Snaps can be hand sewn on, or set with a special metal tool and a hammer. They even have a plier like device. I've written a tutorial on how to use the Dritz snap multi-tool.

Velcro can be used, just make sure to curve the corners and zig-zag around the edge very well, so the plastic backing doesn't stab you in tender places.