Center-Align Posts on Anther Theme

Hi everyone, totally new to wordpress and no coding knowledge, so please excuse me.

I want to center-align my posts. I’m using the Anther theme, which came with a sidebar. In Appearance, I do not have the option to delete the Sidebar.

Here’s a link to one of my posts. You can see the sidebar is empty, but posts remain left-aligned.
https://trashcanteacher.com/formosa-betrayed-a-brutal-firsthand-history-of-modern-taiwan-the-betrayal-of-the-kuomintang-and-the-white-terror/

Thank you beforehand for any help!

The page I need help with: [log in to see the link]