[Plugin: Custom Post Template] Simple step-by-step how-to needed

I’ve just installed the plugin and browsed many of the posts in the support forum. I still am puzzled about where to start, and wish there was a step by step guide for users.

Simple question: How do I create my first “custom post template” so that it shows up in the list? Do I really have to modify the code in certain files or write in php/html and manually upload a file to a certain directory in order to use this plugin? If so, can you walk me step by step through how to do that properly?

Can’t I just designate an existing post with “lorem ipsum” text to become a template for new posts? (wishful thinking.)

Please bear with me, I may be misunderstanding what a “post template” really means. All I really wanted to do was create a template of a post that involves a 2-column bilingual format with shading and indentation in one column, as seen on my site https://www.cssr-scer.ca/ , so that my other co-authors don’t have to do all the table inserting and table formatting steps, and so I don’t have to redo them each time as well. Am I looking at the wrong plugin to create a template for this? Thanks in advance for any helpful replies.

https://www.ads-software.com/extend/plugins/custom-post-template/