SimpleCaddy on the administrator side seems complicated, but is very well laid out. Every product has its properties like product code, price, name and options. More about options later.
This is the main Control Panel of SimpleCaddy:
A simple interface to manage your products, orders and set your configuration.
Let's start with creating a product. Click the product button and then "New" in the standard Joomla Toolbar.
The following screen appears:
For any product, the product code and name are mandatory. The product code can have maximum 13 characters and may NOT contain any special characters like & % or *. Keep it simple with alphanumerical characters and you'll be fine.
Categories can be set in the Configuration screen.
Make sure the product is also Published, otherwise it will not show up on your site later on. Basically you can now save the product and start selling it. Click the "Save" button in the toolbar and you're set.
The Product admin screen will now show your product like this:
Clicking the product code link will bring edit the product properties.