mpcnc 3d printer wants to go out of its range of motion

SOLVED by deleting beginning gcode in slicr

Hello I have a issue with my mpcnc the guys at reprap have been telling me 3d printers need endstops because thats how they calculate machine center. How can I make it so the mpcnc doesn’t go out of its range of motion? It’s lifting itself up because it wants to go lower than the build plate when I hit play. How am I supposed to set the center on repetier ?

Zero is where you turn on the ramps stack.