Place a "named anchor" at the point you wish to link to. You can then easily link back to that anchor.
To create a named anchor, just use HTML like this:

<a name="anynameyoulike"></a>

Then, you can jump back to that point in the page with a link like this one:

<a href="#anynameyoulike">Jump to Named Anchor</a>

To jump to a specific anchor in a different page, just use the #anchorname syntax at the end of the link:
<a href="http://www.example.com/examplepage.html#anynameyoulike">
Jump to Named Anchor in Another Page</a>

That's all there is to it.