To change a setting, type the identifier of the parameter (for example $100 for x steps) '=' and then the new value. Steps/mm needs to be calculated and the easiest way of doing it is by using prusas reprap calulator. The most important part to change is the steps/mm.
Type '$$' and a list of commands should appear, like this: You should see a message like this 'Grbl x.xj ' if you dont see the message, make sure that your are connected to the correct port and use the baudrate of 115200. To communicate with your board you need to open the arduino ide serial monitor. Now with firmware on your board you need to adapt grbl to your specific machine.
