There are a few methods you can use to tune your guitar. This first method works if you already have a good ear and can tell the differences in pitch from one source to another. Using the black tone generator (tuner) at right you will compare the tone it makes with a string on your guitar.
The first “e” shown on the tuner is associated with the fattest string on your guitar. This is called the sixth string. The first string is the thinnest string which is also an “e” string but is an octave higher than the sixth string.
The rest is fairly easy. Click on the first “e” on the tuner and strike the sixth string. Using the tuner peg, turn it in the direction that gets closer to the tone you are hearing from the tuner.
Repeat this for all six strings. Your tuning abilities will improve with time as your ear develops. Also, if your guitar can’t seem to keep the pitch or stay in tune it may need some attention (repair) or you may consider purchasing a guitar that will stay in tune. There’s a Guitar Tuner iPhone app that does much the same thing as the tone generator on this page.
If tuning by ear suits you, you can use the tuning fork method. This method is pretty old school but it can be very accurate.
If the tune-by-ear method does not work try to get a digital tuner that has a meter. See How To Tune A Guitar (with a digital tuner).