Place floorboard in position where you want to install shoe rack.
screw in wall flange to wall only for now. This way you can center the bottom board later.
Assemble from the floor up all the pipes.
When you get to the last tier add a 6" pipe and an elbow to the top pipe and attach it to the wall.
For step 4 its best to have a helper.
Place the right hand bottom side as shown and while your helper hooks the bottom board to the left side you place the right side into the hole to get your placement.
Once you have the bottom board centered you can screw in the wall flange and both floor flanges.
Repeat step 2 again for the right side and finish by attaching to the wall and adding all the shelves as shown.