Sorry - good questions though.
Heres what you need to know, though this is more about HTML than PHP.
Each HTML page consists of a certain number of basic tags. Heres a simple page:
<html>
<head>
Some informational stuff here - header tags, etc. - not the header you see on the page, but service stuff for web browsers, etc.
</head>
<body>
The "Page body" - here is where your header, footer, side bars, main page content and everything else goes. If you see it, it is between a "< body >" tag and a "</ body >" tag.
</body>
</html>
You have lots of code stuck just here and there throughout that page - and some of it adds its own body tag. Not good.
Too many bodies = page orgy. (ok - evil twist, sorry!)
David