I use the same method, front and rear.
I offer the bumper up and stick a couple of screwdrivers into the holes along the top, just to stop it falling to the floor.
Then I line the sides up and clip them onto place, then put in the screws at the sides. Then I pop in bolts/ plastic plugs along the top, but not too tight and then the fasteners underneath.
Once all those are started, I go round and tighten them up bit by bit.
Short, but sweet 'how to' Carolyn. :)