In order to put code on your Code Kitty, you need software from Arduino called an "IDE" (Integrated Development Environment).
There are two ways to get an Arduino IDE:
1. You can use the online version and code your Kitty right over the web! This option is super easy and nice, but it's not free. It costs $0.99/month, but allows you to store your code and settings online and code your Kitty from any computer (but you still need to hook up the USB-Mini cable to put the code on your Code Kitty!):
Please read the instructions for setting up Arduino Create for Code Kitty
2. You can use the downloaded (offline) version. This one is Free but needs to be installed, along with a USB Serial driver, on your home computer. Don't worry, there's plenty of help available if you get stuck!
Please read the instructions for setting up Arduino IDE for Code Kitty