In my experience most php built sites have a bunch of *.inc files that are raw html included in the display code. Eg. header.inc, menu.inc, main.inc, footer.inc etc. Usually you can just "cut up" your existing website into these pieces and paste them into these files so you can have your own design and look. I've built entire websites like this in pure php from scratch. I'm sure the professional blogs would work in a similar fashion so in most cases knowing alot of php is probably not needed. You do often have to take into consideration special keywords and codes that specify where the content goes, but other than that should be copy and paste. If you need some specific help, or have questions just shoot me off an e-mail and I'll do my best to help you out.