okay, coming back to clarify.... this is what I did in pictures.
1. Pic terry flat.
2. Fold 3 quarters of the way up - I flicked the left side of the terry a bit in the pic so you can see how far up I folded.
3. fold back and sew the middle bit along the lines I put up.
Of course this only shows a 1 layer -4 layer - 1 layer configuration.
oh and excuse the scummy flat I used. It was a dye job that went horribly wrong.