First, fold down the top about 2 1/2 inches and sew across.
Cut 2 2 inch pieces of velcro and sew the soft sides at the top on each side. Sew these to the wrong side of the diaper. Then sew the loopy part to the soft side on the side by the edge. (Short side)
Cut a piece of cotton fabric to fit across the area that was just folded and sewn. (Make sure you've allowed extra fabric to fold under all around). Fold and iron the edges to the wrong side.
Next, sew the cotton fabric to the outside of the diaper all the way around the edges. (The velcro is on the other side, make sure you don't sew over it!)
Cut 2" pieces of velcro, 3 to 4 for the middle area, and 4 to 5 for the bottom area. Sew the soft side to the outside of the diaper all around the edges. I used a small zigzag stitch. Discard the loopy part or use for something else. (This image is the bottom of the diaper with the cotton trim on the same side)
This step is optional. Cut 2 6 inch pieces of 1/4 inch elastic. Then about 2 1/2 inches down from the hem sewn earlier at the top, pin the elastic. Then pin it about 2 inches from the bottom. Now pull the diaper and elastic and zig zag it on to the inside of the diaper on bothe edges. Then turn in and sew again to cover the elastic.
To use the diaper, fold in the long sides and fold up twice for a small baby and once for a larger baby, then velcro to the front. Use rubber pants over the diaper if needed. When washing, place the loopy velcro to the soft side before washing. (This image shows the folding for a small baby)