How to flash nodes - Kvel2D/ecs193-wireless-sensor-network GitHub Wiki
To flash nodes you will need the Arduino IDE. You can get it here. After installation, you will also need to make the IDE work with the feather board model. Select "Tools" menu, then navigate to "Board:" submenu, finally select "Board Manager". In Board Manager search for "Adafruit AVR Boards" and install it. More in-depth instructions can be found here.
You will also need Libraries.
When all of these are done, you can open a sketch and press Ctrl-R to compile a sketch and Ctrl-U to compile and upload a sketch. Try to compile first to confirm that you have installed everything correctly.