When you include a page, the code in the included page is included directly into the place you enter it.
For example, if you have a file that looks like this:
A
B
include c.html
D
E
And c.html looks like this:
1
2
3
Then the whole top file, with the include in it, will read like this:
A
B
1
2
3
D
E
So right now you have
Code:
<div id="leftcolumn">
<head>
<title>Untitled Document</title>
// bunch of stuff
</body>
</html>
</div> //this is the end of the 'left column' div
The included file should not be a complete file. It should just be a snippet that fits right into the file its being included into.