Convert Templates to a Website Pages (Minimal Zen Cart Integration)

We have an established website ([login to view URL]) in which we frequently need new pages created and added. These pages are usually pretty simple, our one request is that they be responsive and integrate onto our current website (including our current stylesheets, and our current header and footer). I am the designer and I design these pages top to bottom EXACTLY as I want them to appear on the website, your job is simply to convert these PSD's to working pages, and then UPLOAD THEM to the website and make sure they are working 100%. It will also be your responsibility to ensure these pages are working 100% on all major platforms, including iOS and Android browsers, as well as Safari, IE, Chrome, and Firefox. Our backend is zen cart and knowledge of zen cart is required because we frequently need integrations with it. The pages you will be creating however will NOT be part of a zen cart template, they will simply need to pull information zen cart (like item names, prices, etc.) The first project we need is a redesign of the checkout pages on zen cart. I have uploaded the PSD file with the design for this, find it attached. You will NOT need to create the header and footer, the header and footer are ALREADY COMPLETE. You will only need to create the center portion. This page also needs to be MOBILE FRIENDLY.