1. You need to make sure that you have a blog archive gadget on your blog! To add blog archive gadget, go to Dashboard > Layout > Add A Gadget > Blog Archive
2. After that make sure you have refreshed the page and go to Template.
3. Click on the HTML box and press CTRL+F to search,
4. Search for <div id='ArchiveList'> and paste this code UNDER/BEFORE it.
<div class="widget-content" style="background-size: 360px; background: #fff; border-radius: 10px; border: 1px dashed #ccc; color: #777777; height: 190px; opacity: 0.9; overflow-x: hidden; overflow-y: scroll; padding: 5px; text-align: left; width: 100%;">
8. Now search for </b:includable> , and put a </div> don the TOP of it.