Give a container an id, then use # to refer to that Id.
e.g.
<p>This is main body of my content. I have a footnote link for this line <a href="#footnote-1">[1]</a>. Then, I have some more content. Some of it is interesting and it has some footnotes as well <a href="#footnote-2">[2]</a>.</p>
<p id="footnote-1">[1] Here is my first footnote.</p>
<p id="footnote-2">[2] Another footnote.</p>