You will need 8 Post-it notes for each star and with each you will be making the following shape.
Start by folding the Post-it note (sticky part on the top) in half away from the sticky side then flatten it back out
Then fold the 2 sticky corners to the center (like making a paper air plane) this should cover the sticky area so it wont be a pain later. Now fold in half along the crease
The next step is not hard but it's kinda hard to explain via text so hopefully the video or images will do it, but basically you are going to valley fold the square end into it's self so you end up with a sorta wonky diamond.
Now repeat 7 more times.