design car dealer web site

I need a web site similar to [login to view URL] or [login to view URL] albeit on the smaller scale. I want to do the project in at least 2 steps. The first step is to design the web site structure (site map) and create the mockup screens. -- No actual coding! Based on this I shall prepare detailed specifications for the coding step that should be done in php, using mysql database for car models descriptions and pictures, etc.