In PrestaShop, like in many CMSs, the substance is kept separate from the form. Now that the substance, i.e. the shop's catalog, is nice and full, let's move on to the shop's appearance.
On the web, it is better to start with a pen and piece of paper before throwing yourself straight into the software. The software is only there to execute your orders. If you don't think things through enough to begin with, your hesitations will lead to software errors and you will waste time, not to mention the risk of breaking the shop.
First think about the overall structure of your store before getting caught up in the details.
Your homepage is made up of modules that you can add, edit and configure to get the page you want.
If you have no idea about the overall structure of your shop's appearance, take a look at some examples online and ask yourself the following questions: "What do I like about this shop?", "What do I dislike about this shop?” Find at least three shops you like and three you don't, so that you have a wide range of examples.
Identify the points you would like to reproduce and those that are to be avoided at all costs. It's up to you to apply your observations to your shop.
The Prestashop.com site has a Showcase section where you can find a number of online stores managed using PrestaShop.
Once you are ready to edit your homepage, just find the module or modules you want to work on.