Links are what makes the Web a web.

In music.html find the last of the three img lines.  Make a blank line after it (but before the /body tag).

On the blank line put:

<a href="index.html">First page</a>

Save and view in browser.  Click on the link and it should go to the first page.  You also need a link on index.html to take you to the second page.  Open index.html in your editor and add a link.  As ever copy and paste then change.  Test it.