Code to echo php / mysql on html pages

Hi. I have a website that is pretty much pure html in one directory and I have a php classifieds script in another directory on the server. Show me how to get the listings from each state of the country of the database running the php classifieds running on a section of the same html state page located in the other directory. I just need explanation and one state page done and I can do the rest of the pages once I have the code grabbing the info from the database to echo on the html page.