Group a picture displayed on several layers?

Hello

I'm a beginner with php.
I make a page where a user can choice over many pictures.
Those pictures are displayed on 11 layers.

http://www.jossmontres.ch/atelier/

Now I don't know how I can get or make only one picture,
that I can send it back to the customer when he click on
"Order"!

Could somebody give me one idea how to resolve this
problem.

Many thanks in advance for your help.

Regards

Otto