what i need to build a program like this?

i got this idea of creating an phone app or tablet app , which is basiclly help me with my work at a local pizza place . the part i'm trying to solve is recieving calls and asking the person what he want , write it down .. tell the worker to make it ... this process is so wasting time . what i thought of is creating an app that work on two devices .. one is beside the phone and one beside the working table .. when there is an order i just select it from the app , submit it ... to the other device .... i got a good background about programming , but in this app i don't know where to start .... any ideas ?!

thanks !