Sit down on the closed toilet and examine your surroundings to determine the best spot for the toilet paper holder. Make sure that it is not in the way but also that it is easy to reach. Mark the spot with your pencil.
Remove the hardware from the packaging and determine the size of hole that the screws will need. Put the plate up to the wall and mark the hole spots with your pencil.
Drill holes into the wall based on the spots that you marked. Insert the anchors, if needed, into the wall and gently pound them in with a hammer. Put the plate over the spot and fasten it to the wall with the screws.