Using the QMK Configurator is a quick and easy way to get your keyboard layout designed.
Choose Quantum from the list.
Choose MO - which stands for Momentary Layer turn on. This means that this layer will turn on when holding this key down. Now add the layer number. Note that here, I chose Layer 1 and on the layer list to the left of the layout “1” has turned from grey to black.
Clicking on the left layer 1 will allow you to configure that new layer. Note the downward triangle, means that this key is reserved by the layer below.
This step will make it easier to flash your device in the future as you won't need disassemble your keyboard to press the reset button.
From the Quantum list. Choose “Reset” and add it to your configuration (typically this is added to an obscured layer so that an accidental press doesn't occur).
Now that compiling is complete, the firmware button will no longer be grey. Click it to download the firmware.
*Remember to download your JSON so you can easily edit your configuration in the future.