Show child (sub-pages) on/under Parent page when mouse hovers over parent page

I am completely a novice at all of this. I do not understand “code.” I’m using the theme called “Hashi.” I like the format and set up, etc. I’ve created pages and I want to create “sub-pages” under several of these pages. I understand they are also called “child” pages and they’re supposed to be nested under their various “parent” pages which are the ones I have developed and are listed on the left hand side bar. However, when I create another page, and I use the page attributes to list them under a “parent,” I do so and save draft or publish. But when I get to the site, NOTHING happens and no child or sub page is showing. I do need to rectify that as I do not want to go out to search for yet ANOTHER theme that will do that and have to start all over again. Can someone SIMPLIFY this to help me? Thanks. Coventry27