Database based website

We need an replica of our current site [login to view URL] The idea of the site is for pet owners to post pets they need to rehome onto the site. These are displayed so people looking for a pet can search for the pet suited to them. It allows users to "post" animals onto the site with pictures and a description of the animal. This is stored in a database. Visitors can then search for the animal they want using various filters if required. We also have some admin funtionality like: Moderating adverts Pruning/deleting adverts Sending emails to users (filtered if necessary) We would like a very similar site to our current site but with the ability to place advertising in strategic places to generate revenue. We do not have access to the code for the site. (We can't get hold of the initial web developer)