very easy..just take your bumper off..then i think theres a few screws on the back holdind it to the bumper.Take it off.
get a Gray or possible Red scotch brite pad. Scuff it up really good.dont leave any shiney spots.
Then spray it with some windex(amonia-or proper cleaner) and scuff it wet,(helps get missed spots and cleans)
After you are happy and think you scuffed all cracks and places,Clean it once again with windex/proper cleaner and then with wax/grease remover.
Then just spray it.
assuming your going to use rattle can;Make sure you use the duplicolor paint that somewhat matches your car(no shine) then buy a can of clear coat.