Sometimes it will look splotchy if you do not pre treat it. They sell stuff that you just brush on and wipe off to pre treat, Think its called pre conditioner or something like that.
If it is not bug deal I just brush the stain on with a disposable foam brush and wipe it off with some paper towels.
could not be simpler. of course, use some gloves or something because that stuff is watery and will get everywhere if you let it.