Open structure.html which you created on the page about proper HTML structure and save it as linksinternal.html.  Find the nav element and just below it add a new line just after the /nav.  Put a new paragraph there with the three words physiology, behaviour and location in it.  Make each one a link by placing a tags around it but instead of using a page name in the href put this for the first one:

href="#phys"

That will tell the browser to jump to the element which has the id phys.  That does not exist yet so the link will do nothing.  For the other two links make the href attributes beh and loc.

Now find the three section elements.  Give each one an id matching one of the above links (phys, beh and loc).  The links should now work by jumping you to those sections.

Now scroll down to the bottom.  Just before the footer element paste this:

<p><a href="#top">Back to the top</a></p>

Give the header element an id to match (top).  The new link will now take the user back to the top of the page.

Spots in other pages

You can also jump straight to a point in another page.  Copy links.html from beginnersite and put it in intermediatesite.

Edit the new copy of links.html and paste this after the second list of links:

<p><a href="linksinternal.html#loc">Where koalas live</a></p>

Load links.html in a browser and click on the new link.  It should take you to the third section in the koala page.