Where to start?

So I have experimenting with the UNO, blinking LEDs and such, now I want to get into the big leagues. I want to hack a control board for a massage chair to set my own inputs, and such. Being a complete newb, where do I start. The only skills in hacking I possess is soldering LEDs for an arc reactor (I am a nerd) so where to start? This arduino has opened a whole new world that is very intimidating!

Suggest you start by understanding how the control board works in electrical terms, and deciding what behaviour you want to achieve. When you have completed that you should be able to describe what inputs and outputs the Arduino needs to provide in electrical terms, and describe what inputs the Arduino will receive and what outputs it needs to provide.

Then you need to design an algorithm to produce those outputs from those inputs. Then you need to build and test the hardware and write and test the software. I suggest writing and testing the software incrementally.

Would you happen to know of a good reference site that would explain this further? I understand the hardware involved in a control board, but not the communication process(the "software" portion of the board if that makes sense?). By the way, i really appreciate your help. Thank you!