Start with your dog in the sitting position. While standing beside him (NOT in front of him) put a treat in your open palm, show it to him at nose level and then move you hand away from him and slightly up so that he has to stand to get at the treat. You may have to vary the speed...go too fast and he might not follow go too slow and he might grab it. That hand motion becomes the cue for the Stand. When he becomes proficient, you can add the verbal command...remember, the NEW command (verbal or silent) always comes BEFORE the old command/signal.
Stay is usually taught from the down position which is easier for the dog to maintain but, you can do it from the Sit. Start out toe-to-toe. Hold out your hand like a stop sign and say "Stay". No movement is allowed....Stay means stay. Don't make the mistake of asking for a 10 minute stay without movement right away. Stay takes a long time to teach as it involves both distance and length of time. Work very close and start working the duration first. How long do you want...1 minute? When he's successful toe to toe for that amount of time now, work on distance 5' at 30 seconds, 8' for 30 seconds. That's the distance where obedience work falls apart...at 8'. From the dogs point of view you're in the next county....to far away for comfort...so watch that distance.