The guitar is a great instrument to learn, especially if its your first and you're not particularly musically inclined initially.
If you can play guitar, that translates into being able to play a number of other similar instruments, but also just to be able to apply the music theory which you learn to a number of other instruments.
There are a number of ways to go about getting started, but when you need to learn guitar fast maybe for a performance for friends or as part of a competition, or maybe you just want to learn for yourself quickly without wasting time, there are a number of best ways to approach it.
  Professional lessons are generally not recommended, particularly for those who want to learn guitar fast, that is unless you have a person who is extremely skilled and knowledgeable about the guitar and maybe has been playing for some time now and is willing to spend a great deal of time working with you early on.
Otherwise you'll probably only meet once a week at best and it's not for those who want to hit the ground running.
The internet is a great resource for those who want to learn guitar fast.
One of the easiest ways to learn it quickly is to learn a few of the basic chords, and practice forming them quickly and transitioning between them.
You can find these chord structures anywhere on the net, or I've even written articles on them myself.
Learning or just practicing and trying different strumming patterns with your other hand is the other aspect, then putting them together enables you to play any number of popular songs, most of which are based on and made up of just a small handful of chords..