Making your own retail system

You are the owner of a computer store. You sell several different types of computers. You sell desktops, laptops, tablets and cell phones. Each of these have much in common, they each have a manufacturer,  storage, a CPU, a price and RAM, amongst others. You are to create a parent class that holds the data members and methods that would be common among all devices. You are then to create derived or children classes that are designed to represent each of the types mentioned above. You should have a way of keeping track of quantity of all types that is add and subtract from inventory, a way to find the total value of each type/manufacturer in stock and a way to determine when to order more stock.

Now I have an idea of what the code will look like I'm just having a tough time getting started on the code.