I've seen this on a few sites but I'm not really sure how to incorporate it into my own site. Specifically, say I have a website and I have 3 or 4 different headers that I'd like to rotate as the main header each time the page is refreshed. Is there particular php coding I should add to my header.php file located at my site root or is the coding theme specific?

Also, what coding would be used to make this possible?

Thanks,

Ken

Yes there is a code you need in order to do what you ask.
Look at the files that come with the MSTrenches theme pack. That theme's header does EXACTLY what you ask and if you dig around at it you will find what you need.