How can I add a right Sidebar (second column)?

Hi, I am trying to add a second column (sidebar) on the ride-side of the page. I would like to have the author information on the left, the content in the center, and a new sidebar on the right to which I can add photos and some quick access content. Is this possible? My website is https://tresquintos.cl/, and the code is here: https://github.com/tresquintos/tresquintos.github.io