Multiple select box using mysql

I writing a software catalog that features "experts", who a people especially skilled in a piece of software. My db, has a "software" table and an "experts" table. I need to have a page that generates 2 multiple select boxes, each on with the data from each table. From there one will be able to choose the software program and the experts, which will then record the software-expert relationship in the DB. The problem is that I don't really understand how to populate multi select boxes with db data, and then have the selections passed back as inserts. Can someone clue me in? thanks, Jay __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com