[PHP] Create a Bulletin Board

[Jimmy Bäckström]

Yo!
I'm thinking of writing a bulletin board and I wonder about threads. I want the board 
to be built on threads but I don't know how to do it. I want it to look something like 
this:

subject 1
   |
   |__ reply1 to 'subject 1'
   |       |
   |       |__ reply1 to 'reply1 to subject 1'
   |       |
   |       |__ reply2 to 'reply1 to subject 1'
   |
   |__ reply2 to 'subject 1'

This is important to me so I'm thankful for any help I can get!

//Broder