How to use an electronic tuner
Tuning using an electronic guitar tuner makes tuning your guitar a breeze. Now that you know the names of the open strings, tuning the guitar is a matter of playing the open string, with the tuner turned on, and seeing how the tuner reacts.
Most electronic guitar tuners use either lights or a digital needle to show if the string is in tune or not. Simply pluck the string with the tuner on and see what note displays on the electronic tuner.
From there, move the appropriate tuning peg either up or down until the needle/light stays firmly in the centre of the tuner. This means that the string is in tune.