From your Admin Dashboard, go to Website > Design > Front Page Products
If the product is already listed here, check the box in the column labeled "On/Off" to turn it on. Uncheck this to not display on front page.
To add a product, click on Add New Product
Use the drop down to select a category to choose product from
To have a product be saved to the front page, tick off the items then click SAVE
Note: you can change the order of the products on display by entering a number into the column "Order" - a product numbered 1 would display first.
(Hint* - Don't forget to press the "Save Display Setting" button afterwards! :)