Similar to a classified website

I want to make a website similar to some classified websites online in the market today. I want it to have a login field, that users can create a profile and login to the website so that users that made a profile with my site will be allowed only to post on my site. Very simple site, no flash nothing else complicated. User friendly for me to be able to make updates and change’s on my sites layout. Everything on the site that you will make will be copyrighted and owned by me. I will provide more information about the site privately to whom will want to do the project, but those are the main components at the moment.