I put the above code in and the default header works, but all of the words on the forum are huge, how do I get it back to regular size?
You just need to close that h1 tag, so what you had, you'd just need to modify it to this:
<h1 align="center">
<img src="http://www.asrealasitgets.net/forums/ubbthreads/NEWBANNER1%20copy.jpg">
</h1>