Since towel bars are usually installed onto separate hardware that's mounted on the walls, use the actual hardware as a template to mark exactly where to drill your mounting holes. Hold a piece of mounting hardware against the masking tape and use your pencil to mark the actual spots to drill your holes. Use different-sized drill bits to drill for the two ends. The Molly bolt or wall anchor will require a much larger diameter hole than the screws going directly into the stud. (The size of the hole required for the wall fastener will be marked on the packaging.) Install the wall fastener into the wall, then mount the hardware onto the wall and place the ends of the towel bar over the hardware. Attach the towel bar to the mounting hardware using the screws included with the towel bar. These are commonly small-slotted screws located on the bottom of the end pieces of the towel bar.