Hmm... I think I must still be having novice issues. When I define a variable as you've described, WEBPATH and THEMEFOLDER don't appear as variables. I'm afraid my newness to PHP is probably interfering here. What do I have to do to make WEBPATH and THEMEFOLDER and $ThemeName work correctly (in, for example) a php file that I am including.
Thanks in advance, and if this question is just too basic and stupid to answer, I totally understand.