Ramps 1.4 with Mega2560- Marlin Help

hI All
I am a newbie in this field of electronics. I am wanting to build a simple Laser cutter/ engraver. I have been all over the internet and every one mentions Marlin as the firmware. Does any one know on how to re program the configuration to the following . I am using 1 Nema 17 stepper motor for the x axis and 2 Nema 17 stepper motor for the y axis. Laser Diode will operate on x azis. I will not be using any other of the other functions of the board. The program needs to just work on a single x axis and a dual y axis. Attached is a picture of what im tyring to build . I have know Idea where to start. I have all the electronics but need assistance is getting the axiis's configured in Marlin so I can start testing the motors before I install the laser diode.

simple laser engraver.JPG

hi AndrewMclaren,
see here:

and especially here: