Let's get familiar with the basics of the PrestaShop back office administration that relates to the theming of the shop front or front office of your PrestaShop store.
Now, using the default theme in PrestaShop, have a look at your current storefront and how the theme is governed by the back office control. By looking at this, you can tell which back office item you need to modify, replace, or set according to your needs.
Basically, the layout can be seen here in the following screenshot:
Now this is how your back office administration panel, which controls these blocks, should look. ...