Teaching your new puppy Sit & Down.
For this you will use a food lure, which is basically "attaching" the dog's nose to "oh this smells good." We can use that to lure them into many positions. Its how we first teach most new behaviors.
Sit: Place the food in the dog's nose and slowly move it up and over their head. Wait until their but hits the ground and say "Sit," followed by "Good" and a tasty treat (or other reward your dog enjoys).
Down: First place your dog in a sit and reward. Then place the food in the dog's nose and very slowly move it straight down to the ground. Pause here for 1-2 seconds, then very slowly pull the food forward along the ground. Wait until the dog's belly hits the ground then say your "Down, Good!" and reward.
Sometimes it make take several tries to get your dog to do this. Don't get frustrated. If you're having trouble training one of these, especially Down, and its not going well, take a break and move onto something else or play with your dog instead. Try and always end training on a happy note. Be patient and it will happen.
Other helpful Blog articles:
Teaching Down Puppy Nipping
Helpful Ways to Exercise your puppy
Come When Called: Step One
Come When Called: Step Two