[Plugin: WordPress Goodreads Bookshelf] Not working as widget

Hi, I followed both the installation instruction and the instructions in this post but when I finally did get Bookshelf working, it threw off the entire layout of my blog, with all my posts ending up underneath the shelf to the left instead of in the central column where they belong. Please help.

https://www.ads-software.com/extend/plugins/wordpress-goodreads-bookshelf/