First have the dog sit: pull up and back on the leash, while putting your fingers near the nose to pretend you have a treat. Once you have their attention, lift your fingers up above the head, to rock them into a sitting position. Say name and "sit" firmly. Once the dog sits, DO NO REPEAT. SIT-NO-SIT. When you say "No" pull back on leash with a quick snap on the leash not a long pull. If you need to push down the butt, push down on the hip bones near the tail and say, "sit" firmly. Do not keep pushing down after 1- 1/2 days. Once they understand the command then say, Sit-No-Sit but don't give up. Always make them do any command. They don't know minutes but they do know a time frame so if you give up one times they are patient enough to wait longer, so eventually you will give up again.
