Establishing a child theme & modifying sidebar

I hope someone will assist me in this forum, as there has been no reply in weeks on the forum for my theme, Thistle.

I am trying to establish a child theme, so I may upgrade to the latest version of WordPress without losing the changes I made to my style.css file. Did I do this correctly by making a sub-folder in the theme folder, and then uploading the style.css file into it?

I’ve been trying to modify or eliminate the list in the left-hand column. I want to remove the blog post date and the words admin, can’t comment & edit. I can see the code when I go to “View page source,” but can’t figure out which php file has this code. The website is located at https://www.shaughnadkins.com. Any assistance from this forum is most appreciated. Thank you!