I normally sit on one long side or the other. I call the long axis X and the shorter gantry motor(s) Y. Z is vertical.
When you run gcode that you got from someone else you need to check that the directions are set up as you would expect. It may have been set up for one of the "wide routers". The material you are going to cut may be rectangular and oriented 90 degrees to the way the gcode is going to cut it. Not usually a disaster, but it depends on how expensive that AAAAA quilted maple guitar body blank was.
CarveOne