This is the most common method taught for tuning a guitar to itself, by comparing a note played on one string to an open string.
When you use this method, try to be accurate. The effect of one string being slightly out of tune, compounds with each additional string!
Tune the 6th string to low E. Use the online tuner, a piano, a pitch-pipe, or an in-tune guitar. If none of the above are available try it by ear.
If you have no idea what the low E string is supposed to sound like, check if two or more strings are tuned to each other and start there.
Tune the open A string to the low E string at the 5th fret. The notes are named "A".
Tune the open D string to the A string at the 5th fret. This note is "D"
Tune the open G string to the D string at the 5th fret. This is "G"
Tune the B string to the G string at the 4TH fret. This is "B"
Tune the open high E string to the B string at the 5th fret.This is "E".
Another method to tune guitar to itself is by using harmonics. I found that when I tune a guitar using harmonics, it works well on guitars with high action.