Back End development for ecommerce site

I'm a graphic designer in need of a website to sell shirts I design. I will supply the graphics and layout for the site and have supplied a few screenshots to give you an idea as to what it will look like. The design isn't 100% complete but should give you a good idea as to what the project will require. [login to view URL] [login to view URL] [login to view URL] [login to view URL] Your job will be to design the back end of the site around my design using PHP and either a open source ecommerce platform or your own preferred ecommerce software.