Fold the other pieces in half and pin. Sew them closed using a 1/8 seam allowance down the long edge only. :) Backstitch at the beginning and end!
Push a safety pin through one side of the fabric near one end of the tube and push the head of the safety into the tube. Scrunch the fabric on the safety pin, pulling the edges toward where the safety pin went in. Keep scrunching and pulling until the fabric begins to turn. This is honestly the worst part of the whole project! Everything is smooth sailing from here on out, I promise!
If you're having issues with turning, check out this tutorial
Once you've turned the tubes right side out, iron them flat so the seam is on the back of the tubes, like the last photo shows.