First, what device?
I never used CCS C, but most of the compilers come with rather detailed documentation about their supported functions. Also, reading the datasheets is pretty much mandatory if you want to understand how things like interrupts work.
EDIT: I'll assume you're using the PIC12F675 like your last poast
In any case, you probably need the comparator interrupt, which means you'd need to provide a reference voltage on another pin. Or you can use a timer interrupt and check every 10 ms or something for pin status changes. It would probably be easier.
Here is a tutorial on interrupts, it also recommend reading the help file.http://courses.ece.uiuc.edu/ece445/wiki/?n=Topics.PICCCSCInterrupts
EDIT2: Ewww, the tutorial seems to have a 20ms delay inside the ISR... that's very bad, don't do it!