Assuming you are attaching a new cabinet to the wall:
1. Begin by measuring the area where you will be attaching the cabinet. This will give you an idea of what size cabinet will fit best in the space.
2. Once you have selected a cabinet, mark the location of the studs in your wall on a piece of masking tape. This will help you know where to drill holes for screws.
3. Drill pilot holes into the wall at each stud marked on your masking tape. These pilot holes should be slightly smaller than the screws you will be using to attach the cabinet to the wall.
4. Affix brackets to the back of your chosen cabinet using screws (drill these into place before attaching them to the wall). The number of brackets you use will depend on the size and weight of your particular cabinet.
5 .Lift your cabinet into place and line up the pilot holes with those in your bracket. Screw your bathroom wall cabinet into place using 2-inch wood screws driven through washers for added stability