I also have a DIY CNC based on Arduino/GRBL-shield, main interface is Easel and it works just fine.
In Easel click “Set up your machine” under the Machine tab. Follow the instructions, it doesn’t really matter wether you choose Shapeoko or X-carve as type.
Use the setup to verify/correct x/y/z-travel.
Once that is established run the machine and adjust travel (steps / mm setting)
That is basically it 