Question

They want me to start with one triangle and add 2 tooth picks each time but how do I do that

Answer 1

add them all around the top pointing down

Answer 2

if you have three toothpicks first, you have 1 triangle. If you add two on each time, you add it on to the existing triangle, which means you use one side of the existing to form the new one. 

Let me know if you don't understand!  :)