It is easily possible to link items in the same document for the purpose of creating a menu for the page or just to point important parts of a page.
Now below is a the correct way to link within the same document:
<a name="top">title of the document been linked to here</a>
<a href="#top">name of the link here</a>
Notice the name of the link inside the code ("top")
This can be anything you want it to be but note that this name must also be in the actual link code ("#top")
you can create as many of these as you wish just name each one differantly as you go along.