You will have to flash your board. It is quite simple, once you've done it, but it can be a bit daunting at first go.

Look at this video: http://www.youtube.com/watch?v=sOojWpuci_o

Although it is for the Makerfarm Prusa i3, the basics are the same for any RAMPS 1.4 Arduino board. You could download the MakerFarm RAMPS files to give you a starting point, but you will have to do some trial and error work to adapt it to your printer.

You are lucky. If you hit a brick wall, come back here with your problem and someone will be able to put you right.

Old Man Emu