You can learn how to play the guitar by enrolling in guitar classes, you can ask a friend that knows how to play the guitar to teach you or you can choose to learn by yourself. If you choose to enroll in a class, everything you need to know will be taught in the class but if you choose to learn by yourself.
Here are some steps to guide you.
1) Buy a guitar: get a new or an old guitar to practice what you have learnt.
2) Use some of the free tutorials online.
3) Start by learning the basic guitar chords.
4) Get song tutorials online so you can practice the chords you have learnt.
All that you need to perfect your skills are on the internet.