UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? posting a picture in the header

I want to learn how to post a picture as a header at the top of the forum page.
From what I've figured out I go to the CONTROL PANEL- GENERAL- HTML INCLUDES.
But lets say I have a picture saved to my hard drive or on photobucket....what is the full HTML code to place the picture at the header space. I would want the pic to be centered, not to the left or right.

Thanks