First, you will have to gather your supplies. You will need a board at least as wide as your wire rack. I used one from a black entertainment center we were going to throw).
For the next step, use your tape measure and figure out the distance between the metal posts. Use a square to make sure they are straight.
I laid out the tape in straight lines, and marked with the tape measure where to drill the holes. The tape was to help minimize the particle board chipping.
I used a drill bit the same size as the as the posts. After the first set was drilled, I removed the tape and put the first rack in to see if it was correct. I used a soft mallet to pound the rack in
I finished drilling the holes, slowly removed the masking tape, and colored any chipped areas with my black sharpie, and put the rest of the racks in using the mallet.
The holes I drilled were tight enough, and deep enough that I didn't need any adhesive to make sure the racks stayed in place.