hey man, i am going through the same exact thing right now, I had surgery last tuesday. This is my second ACL repair, and I hate to break it to you, the first three weeks after surgery are going to be the most painful days of your life. Unlikw yours, they took out of my hamstring to make a new ACL, so its a little different. The thing that is going to cause you the most pain in the swelling and bruising(and im guessing you are about to really start bruising, mine is black and yellow and red) but anyways, the best thing to do now is just get on a scehdule with your meds, dont try to act tough and not use them cause you will regret it, trust me. Just keep it elevated and iced as much as you can, and start kind of massaging around it to help with the swelling. I hope ths helps some with the pain, but remember to not let your meds wear off, that is the biggest thng.
And as far as putting weight on it and lifting, lift only as much as you feel comfortable doing, and the same with putting weight on it, just as much as you feel like. Like I said, this is the second time i have been through this so i feel for you.
When you start rehab and stuff, you best bets are cycling and swimming. Swimming being the better of the two because it relieves stress on the joints. Also use this as a way to train from here on out, you will thank yourself. I hope this helps, if you need anything else, you can e-mail me at firstname.lastname@example.org Good luck man, I know it sucks, keep your head up.