I would just buy a concealer that is the same skin tone as your foundation, use a concealer brush and dab some concealer on your pimple. Do it little by little so you don't overdo it. Once you have used concealer on all of your marks you want to cover, use your foundation all over your face; overtop of the concealer too. Sometimes it all depends on how good the brand is you are using though. Make Up For Ever, Bobbi Brown, and Bare Escentuals have good concealers.