Add additional right sidebars to theme

I am a beginner. Some old friends and I have started a new business and I am trying to build a website ( https://www.kssaustin.com ). I have over 20 pages but have only 4 right sidebars that I can use. I would like to have different right sidebars on most of the pages. I don’t know how to add new right sidebars. I have read the online information, watched a video, and downloaded a plugin, but still don’t know how to add the sidebars.

Please help if you can.

Thank you.
https://www.kssaustin.com