Watch the Tuning the Guitar online guitar lesson by Richard Gilewitz from Jump Start Fingerstyle Guitar

I’ll show you how to use a tuner to tune your guitar and some string-stretching tricks that help new strings stay in tune. Use delicate motions and move slowly when tuning – that will make it easier.
You can also tune a guitar by ear, which I recommend to develop your ear. I’ll show you how to do that – you can always check each string with your tuner, but this way you don’t rely on the tuner as a crutch, and you develop your ability to hear pitches.