need some help on building discussion board

I have a mobileme account and am using iweb to build my site. I need a forum/discussion board so that the group of people who go to the site can post messages instantly in one place...

any suggestions?

you'll have to write something in php with a database, or find somthing open source

I don't think you will be able to do this with mobileme. You will need advanced hosting.

If you know how to install PHP scripts you can download PHPBB. Free open source message board.

If you don't have any clue about PHP and what not you should look into a service that will host/setup for forum for you such as Create your own free forum, FORUMOTION - Make your forum for free

SMF forum is very good also. Free also.
www.simplemachines.com