Many people start out recording an acoustic guitar, often utilising a pickup. That can get an acceptable result, but you only really get that natural acoustic sound when you use a microphone.
But where do you start with microphones? What is the best one to use? Where is the best place to put it? Can you use more than one? The answers to these questions are long and complicated, but here is an article from Cakewalk dot com that is a great starting point.
And remember, the answer to most questions regarding recording techniques is “Experiment”!