breast feeding troubles

My son is 3 weeks old. I been having trouble breast feeding since he was born. He wasn't latching on at all at the hospital and I wasn't suppling that much breast milk to begin with. I have tried when I got home to breast feed but he is not having it. Plus I have flat nipples so for him to even latch on has been a challenge . I have been taking medications since I had a c section but I recently stopped. I guess what I'm asking is how can I produce breast milk!? I want him to get the best nutrition as possible! I need help! I really want to breast feed.