grbl
First download from here >>>> firmware.zip
Firmware grbl :
Insert your com port number like "com4" and press "Enter" and imediatelly press reset button from arduino module.
For comunicate with costycnc foamcutter you needed a gcode sender.
You can use gcodesender from chrome store : https://chrome.google.com/webstore/detail/gcode-sender/ngncibnakmabjlfpadjagnbdjbhoelom?hl=en
or download another gcodesender da qui :https://github.com/winder/Universal-G-Code-Sender/releases