A few questions on programming the Control System

[Avarik]

First off, let me start by saying I really don't know C too well. I am having a hard time programming, but I am attempting to do it anyway. Now...I have a few questions for programming the control system.

Firstly, how would I set up a system to push 1 button to open and close pneumatics? I was thinking about having a state which is altered if the button is pushed, but I cannot figrure out how to do this (from decleration to initialization to writing the code!)

Secondly, how do I create a program which will overide all other code and execute a set of commands? This would be to use pneumatics to shift gears in a gearbox. I am unsure how to program the code, and set up overiding the system. I was thinking about using interupts, but I don't know how to call them (I have Kevin's code with the interupts added in.)

Thanks in advance! Any help is appreciated!