hmmmm well it depends on the type of scaring
for red marks left after previous pimples or possible popping or picking
those are called red macules or something they are the bodies healing response and will usually fade naturally over time usually they will go away in 6 months or soo
actually they arnt scars at all
sometimes acne scars can hyper-pigment and turn like brownish red purple ect
they are usually exasperated by sun exposure
they can be eliminated with the use of tretinoin usually called A-ret or like retin-a or somthing
for other types of scaring ie, icepick, and box or like deep scars you usually need to see a professional
they will usually do some form of chemical peel or microdermabrasion
i have personally used nutragena acne mark fading peel
it contains salystic (not spelled right) acid that when used over time can fade some old red marks in such
the best thing you can do for acne scars is
DO NOT PICK AT THEM
it only makes things worse
hope this helps
if you have anymore questions just ask I'm an open book