SKT Black Customizing

I’m very new to WordPress and can’t seem to find the instructions / guide to customizing the SKT Black theme I’ve working on locally. The standard pages have code creating the headings, layout, etc. and I want to be able edit the page. For instance, the Home page has a predefined settings. I know I can right click on the page and select Inspect Element and can see the code. How do I access this code on order to edit it? Do I need an add-on?

I’ve not been able to locate with the Help section.

Thanks,
Newbie and Not a Developer