The first thing you need to learn to tune your guitar is the notes that actually need to be tuned. We will be using standard tunning. Starting from the top string, which is the lowest note, the strings should be tuned to the following notes: EADGBE.
The first E note is low E, below middle C
The next string is A, below middle C
The third string is D above middle C
The fourth string is G above middle C
The fifth string is B above middle C
The last string and the highest note to be tuned is E, second E above middle C and two octaves above the low E string.
Loosen the tuning pegs on your guitar. Then tighten them one at a time trying to match the the pitch of each string, as closely as you can.
Once you have tuned all six strings, go back and check them again. Sometimes you’ll have to make some minor adjustments. Remember practice makes perfect and you’ll do it faster with practice.
The best and most precise way of tuning your guitar is with an electronic guiter tuner.
Tuning Your Guitar By Ear
This method is not the best solution. Especially if playing with others but ...