Ok so My Project for this upcomming Year is to Turn one of my Desktop Computers into a Server. Is there a free/cheap way of doing this.

Also I was wondering what Knowledge I would need to create a Forum sorta like this. I dont want to use free forums cause I wanna create My own. I want to run the forums off of the Desktop Computer/server once I get that up and running.

Any Suggestions on what I should start learning to go about and create the forums and Server.