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.