The easiest way to teach sit is to take a nice smelly treat like sliced turkey. Hold it just over his nose and slowly bring it backwards behind his head. Say sit as you do it, then hold it still for a bit. He'll sit naturally to get a good view of the treat. Make a big deal out of it with loads of praise and treat. Practice every chance you get! Do it in training and For fun and try it when its time to eat, etc.
Keep training sessions short maybe 10 min focused on one thing, but do several sessions each day. I did not teach one thing at a time, we did sit in the mornings and at feedings, then practiced his name outdoors with come and fun hand shakes in the evening.
Teaching him come and his name is fun and easy if you have two people. You can do it indoors or out. Have each person stand about 10 feet apart with treats and let him smell the treats each person has. Begin by having one person call his name and really play it up with lots of clapping, and repeating come! When he comes to you, treat & praise. Then have the other person do the same, keep going with the name & come, back and forth until he gets tired. After a while, you'll be able to do the same round robin without the treat. The earliest you begin teaching his name and commands, the easier it is for you. They tend to get a little stubborn as they age!
The more fun you make training, the more your pup will enjoy learning and will aspire to please you.