Step 6: Preparing The Launcher!!
Now take your right hand and make the funky shape shown in the image. The goal is to have the fleshy part below your thumb fit directly below your left thumb, making the most airtight cup with your hands as possibe. To test it's airtightness, blow into the hole. If it's really hard to blow into, you're probably doing just fine. If not, perfect your technique. (Yay I fixed the blackness!)