If you want to tune your guitar then you will need a guitar tuner. The Seiko ST-757 is a chromatic tuner that can tune it for you. Chromatic tuners are very simple devices to use. You connect your guitar lead into one end and start playing strings. The Seiko ST-757 has an input and output so it can be used independently or in conjunction with an amplifier.
Plug an audio lead into the output on your guitar into the "Input" of your Seiko ST-757. You can also plug another audio lead from the "Output" into your amplifier.
Press the "POWER" button to turn the tuner on.
Strum or pick one open string on your guitar.
Adjust the tuning peg on your guitar until the tuner shows the correct note. The standard E tuning for guitars should be: E, B, G, D, A, E (from thinnest to thickest string).