You will need to visualize your end result. Let's start with the aim to create a theme with one column on the main page.
First, how would you get ideas for theming for PrestaShop? Get a blank piece of paper and scribble to make it easier for you to work on your mission. If you need some ideas, search for some nice websites and get the idea on paper.
Start with http://www.prestashop.com. There is a live showcase of PrestaShop stores that were built by the other users all over the world (we talked about this in the first chapter).
There are some other websites you can search from where you can get ideas. Here are a couple of them:
Once you get some idea ...