SEO friendly URLs

Hi, Our website [login to view URL] was made in PHP and Ajax. It has a database running with clients information. We had a developer changing the URLs to a more friendly structure but the job was not finished. We want to turn the website SEO friendly so that Google can index all pages. Some pages still have an old URL structure that need change. We also have an administration area that client's and ourselves can access to edit adverts, create new regions, add countries etc. This also need to use the new URL structure. Please bid only after looking at our webpage and if you have experience in Ajax, PHP and you understand what the problem is. Thank you