Basic process is:
Sketch out idea
Show it to target market, get feedback
Build 'MVP' (minimum viable product) which doesn't even necessarily need to work
Show it to target market, get feedback
Take feedback to someone with some cash, relinquish them of their cash and use it to build first version of full product
???
Profit
Feel free to PM me if you want to give some details, I haven't got time or inclination to steal it