Include (Newbie question)

Hey, I have just being going through the manual (windows version) and am a bit confused about "include", If I want the scope to affect the whole page I do this right: (example page) <html> <body> <?php include blah.php ?> some html <?php use some functions to call blah.php ?> is this correct? and my second question is if I am including a html file will that file need to have a <html><head><body> etc etc or you must have the <html><head>etc only in one file? Since am confused about this and it comes straight from the RTFM() function.....any help appreciated. :-) Cheers, -Ryan.