Have you taught your dog place yet (or Kennel)? Have you gone through FF? You need to teach him steadiness to command. Make sure he stays in the spot until you tell him to go. Basically you want to tempt him with whatever you can to make him want to get up, and then correct him when he does so.
First things first, you need a dedicated location for him to sit or whoa at while you are tempting him. A raised platform works best because it is easier to correct him when he jumps off. Have him "place" on it and then begin the tempting. Correct him every time he comes off without your say so. Start with movement, toys, food, gun shots, whatever you think might make him move. If he still doesn't move then this is how I finish the training:
I don't know where you live, but I live in the country so I don't have to worry about neighbors looking at me funny, btw. I took an old broom handle and drilled a hole in one end. Then I tied about 6 feet of clothesline rope through the hole. I tie the free end of the rope to both feet on a pigeon. I place my dog, then I let the pigeon freak out in front of him. If he breaks I pull the pigeon to me, correct him and do it all over again.