Well, you're obviously going to need an amp. And not just any old amp . . . a lot of companies make amps specially designed for the sound and tone of acoustic guitars. I know Line6 and Peavy both make these (go to their websites for make and models).

And you're going to need some way to get the guitar to the amp. The most common way to do this is with an acoustic pickup that mounts in the soundhole just below the strings. I think they also make little mics that go inside the body of the guitar. Go down to your local guitar shop and find out what they have.