How can i get rid of post acne scars?

i dont want to spend loads of money and i want quick tried and tested results. thanksHow can i get rid of post acne scars?
my son has been using pine tar soap for a over two months now. it has really helped clear it up. he had it really bad. huge sores on his face, back and some on his arms and chest. you can get it thru your pharmacy. it costs about $4 a bar and a bar can last 3-4 wks. His skin is 100 percent clearer now