Fixing a shelf with brackets is the easiest and most common method. Just make sure the shelves are cut to the right size.
Draw in pencil the location of the holes to be made to fix the brackets on the wall. Help yourself one level.
After placing the appropriate dowels, screw the brackets using an electric screwdriver.
Put the wooden shelf on the brackets.
Make sure the position and the correct horizontality.
Screw the tablet onto the brackets.
The length of the screw must be less than the thickness of the tablet.