You should be using low voltage Box. It should look like this! They have them at Lowes and Home Depot also in the electrical area. I got most of my Network stuff including these things from Monoprice. So most of mine are black in color.
Basically, it allows you to screw on a Keystone cover. These things have 4 small holes in each corner. Use a small level to level it. Mark the 4 holes. Draw your lines from one hole to the next. Cut the drywall and then mount this box. It couldn't be simpler.