Add a sidebar (make theme 3 columns)?

I found this article for creating additional sidebars: https://www.blogohblog.com/adding-extra-sidebar-to-your-wordpress-theme/ Although I found a funcitons.php file in the theme folder, I’m not seeing the exact line where I would edit the number of sidebars to register, as stated in the article.

I’m using the pro version of Sugar and Spice. Is it possible to add CSS code into Custom CSS?

Here is my site: htt://thereswool.com