Or ColdFusion, Ruby, ASP.NET, MSSQL, PostgreSQL, etc...
You CAN do it with Dreamweaver, but you need to know programming and database management. Just like you should know XHTML and CSS to build a website.
Depending on what you want to do, you might be able to find a solution already existing. Something like vBulletin (costs money) that this site runs on or phpBB, PunBB (my favorite), Vanilla, etc.