Creating a simple style..
 

Basically, i want an header image and i want users to be able to click parts of it that takes them to certain forums, maybe even a log in box on it aswell..
How would i do this?

Also,

How do i set forum width?

Edit your header template and play around with all u wana do.
Forum width can be changed many ways.. one quick one is editing spacer value.. Edit style options Main Table Width = you change lucid or static.. % or Px

I think he means like a header that, instead of clicking any part of it takes you to the forums index, is using image mapping, where clicking certain parts do different links.