You can get this template HERE.
Cut our your body and snap backing PUL cuts.
I use a washable glue stick to temporarily hold them in-place.
Mark your front panel snap locations except the top umbilical snap.
Apply your snaps.
Using a 3-step zig-zag stitch, sew on your fold-over-elastic. Stretch tight through the legs and across the back, but keep without tension around the wings and around the front.
Close up showing stitching and the stretching tension changes:
Add your top umbilical snap.
Add your wing snaps.
Showing the wipeable PUL inside:
The fit over a small fitted diaper:
The fit over a newborn fitted diaper:
Templates can be downloaded here: http://prefold2fitted.blogspot.com/2012/10/online-free-downloads.html