Screw the steel support rail to your wall at a sufficient height that the vertical supports will be clear of the floor when hanging from it. Snap the rail cover onto the rail to hide any unsightly screws.
Hang the vertical dividers on the support rail, hooking their suspension brackets over the top of the rail and locking them into position. Position the dividers to be equidistant, with just enough space between for your shelves.
Insert pegs in four holes at a single level between two of the vertical components. Place a cam-lock shelf on top. Screw the shelf into place and repeat the process for each vertical shelf area to secure the closet structure.
Add the custom components of your closet as desired. Every part of the closet works on the peg-and-hole system — rest a shelf on four pegs, attach a sliding rail and install a drawer, stick end caps into the holes and rest a hanging bar between them, snap a tie rack into a hole, and so on.