According to this chart you can see how the guitar is tuning. You must remember carefully E 6th is the low note and E 1st is the high note. Between this two strings tone frequencies are increasing ascending.
Few methods to tune a guitar
Method 01: You can use a electronic tuner to tune a guitar. When we touch the string the tone frequency detect by the tuner and show it. Then we can change the string tune using tuning key on the top of the guitar neck. This is a very easy method to tune a guitar correctly. A sample guitar tuner is following.
Method 02: You can tune a guitar using a keyboard. Touch a key you want and listen carefully. Then tune a string as you want. In this method you must have a correct and well identification ability a tone.
Method 03: If you can recognize tone frequency correctly you can use this method. First tune E 1st string using any equipment. Then touch the 5 th fret in B 2 nd string. Then pick E 1st string and B 2nd string. Hear carefully both tone frequencies. Tune the B 2nd string using the tuning key to become same frequencies both strings. Then touch the 4 th fret of G 3rd string. Pick it with the open B 2nd string. Compare these two tones as below and tune G 3rd string.
As below steps you can tune other strings. Tune 5 th fret of D 4th string to open G 3rd string. Tune 5 th fret of A 5th string to open D 4th string. Finally tune 5 th fret of E 6th string to open A 5th string.