After you have created your products (or imported them), you must apply a Featured Image to those products.
There are two options where you can enable Featured Products as seen on homepage.

Go to list of Products and click on the star icon as seen in the screenshot below.

If you want to do manual, the instructions are below.

Go to the Edit Product and in the Publish box, you will see "Catalog visibility: Catalog/search"
Click on 'Edit' and enable the checkbox where it says 'Featured Product'. See screenshot below.