Layout to stay the same throughout store

Thank you in advance for any help you can give me. I'm setting up a jewelry store and up 'til now I've come up with this design: http://www.joyeriasuny.com/prueba . It's simple but elegant and to the point. I plan to use that same design for a zen-cart store, the problem is I don't know how. So far I've been able to edit define_main_page, stylesheet, tpl_header and tpl_mainpage and I haven't been able to match original design. This is the store: http://www.joyeriasuny.com/joyeria and this is the layout http://www.joyeriasuny.com/prueba . What do you suggest, and where do I insert the tables so that they're the same for every page that there is? In case you don't understand, I'm planning to use the same layout(the one I designed) for every page(including categories, shopping cart, etc., just as the background and header are the same) Thanks again!