I couldn't figure it out for a while, and I'm not sure I do it correctly, but it works! I take the sides and snap them to the top line to fit around the waist. Then, for my youngest, there's too much extra in the crotch area, so I snap the two on the leg to shorten. For me, I pull the second snap down to connect with the one directly below the waist snaps. Good luck! I'm getting ready to hit that sale tomorrow morning!