Mu is a simple code editor that works with the Adafruit CircuitPython boards. It's written in Python and works on Windows, MacOS, Linux and Raspberry Pi. The serial console is built right in so you get immediate feedback from your board's serial output!
Download Mu from https://codewith.mu. Click the Download or Start Here links there for downloads and installation instructions. The website has a wealth of other information, including extensive tutorials and and how-to's.
Now you're ready to code! Lets keep going....