Need help reattaching the front and rear bumper valance on 06 Grand Prix

I accidentally pulled off the front and back bumper valance on my 06 Grand Prix. I know that i will need to replace the bolts on the sides and middle to keep it in place. I am having problems getting the plastic squares to lock into the bumper. I was wondering if there is a special process on how to do this or any guidance you could provide. I have put together a document with a diagram and some notes. Your assistance would be greatly appreciated.