I found a css code insert that works. This will add two buttons:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<li id="button1">
<a href="https://www.google.com">
Purchase Prints
</a>
</li>
<li id="button2">
<a href="https://www.google.com">
Get Notified
</a>
</li>