This is where the CSS for the page is inserted.
This should always be present in the template file unless
you've made the appropriate changes in other parts of the script.
Various parts of the application depend on values that are defined in
CSS that is inserted here.
If you know what you are doing it would be best to put this CSS in it's own file and then call it using something similar to:
<LINK REL=StyleSheet HREF="style.css" TYPE="text/css">
Not cluttering up the top of your html document could help you out in with the search engines.
These are the links that the user clicks when they want to perform an action, for instance "edit", "search", "register", etc. .
It is also where the "home" link resides.
If you know html you can go into this function and change it to suit your needs. Then in your template file you can insert this function call to put the links wherever you want in the page.
This is where the main content for any particular page is displayed.
The content depends on which page is currently being displayed.
If you are on the search page, then this is where the search results are displayed. If you are browsing ads, this is where the results are displayed. If you are browing categories, it's where the sub-categories are displayed.