Adjusting “Older/Previous Entries” Listings

Hello everybody,

I’m embarrassed for not knowing the answer to this question, but I think I’m not googling the right terminology. I’m using this simple wordpress site based mostly on a template helpfully provided by Jonathan Wold:

https://www.kingofrpgs.com/

My problem is… I can’t figure out how to cause the older entries to be hidden behind a link saying “Previous Entries” or “Older Posts” or something like that. Instead, all the entries I’ve made so far are listed on the front page of the site, and the site is taking longer and longer to load.

I think I may have unwittingly deleted the code which governed this. How do I add it back in, and how do I determine just how many posts will show up on the main page and subsequent “previous entries” pages? I’d really appreciate any help.