PHP Sales and Order Form with Administration Backend

Project Idea: I have designed a professional website where advertisement has been placed through an open ad software. For each ad an external link has been placed. I want to enhance my website by offering advertiser the opportunity to promote and to sell their products and services (which has been ap- proved by us) to our potential website visitor. For this we need the implementation of code (mainly) in PHP and mySQL. Furthermore, HTML, XML and CSS is required to create professional sites. Clientbase verification should be done with JQuery and JavaScript. It is understood that Values entered in PHP and HTML form should be validated with JavaScript and JQuery code on the client side. Values entered in PHP and HTML should be validated with PHP regular expressions on the server side. It is very important that the each page is hacking save. Also it should protect against Cross Site Scripting and SQL injection. I need a complete website solution that allows the customer, the advertiser and the owner of the website to interact and to perform all tasks required for selling "products and services" trough this website. Also it should be possible to manage and to invoice the advertiser for each sales request. YOU need in the first instance to present us, how you would design the website solution. For this you need to work out the optimal workflow between each role partners (administrator, advertiser, customer) and all required features in this process. The specification needs to be professional, but not "over" professional. We will then verify the paper and may give you some further points to work out that is missing in the paper. Later you need to implement the idea in CODE in a professional manner. We will check the website solutions for any errors or bugs.