Marlin offsets issue!

I am new to 3d printing and I am having a bit of trouble!
I am using this firmware on a RAMPS 1.4 board.
I want to adjust the offsets in the image above but I can't find the commands to set them. I can set the XYZ values using the M666 command, but I can't find the LRF commands for my firmware. Or does my firmware not have these offsets?

Edited 1 time(s). Last edit at 04/10/2015 01:38AM by Beng_.