Scripting for android platform?

How to do scripting for android platform? I am trying to make a game for android phones but to do that do I have to make change in my code or else I have to do from scratch?

You dont need to change too much, unless you made your game use keyboard keys, but if you go to file → build and run you will see a window pop up with options on the type of platform you want to run your game on. Then select android, click player preferences and change whatever you want.