- Not sure if you are counting the strings right. Bottom string is 1. 6th string is the thickest one (low E).
- The letter should match the note you are playing.
Use a reference pitch to tune to (not sure what this site has, so I'll link a generic one). Your strings should sound the same as this:
http://www.gieson.com/Library/projects/utilities/tuner/
If your guitar sounds OUT OF TUNE (doesn't match the sound of the reference notes)
- Then it is out of tune. Just showing a green light doesn't mean you are in tune. It means you are in tune with the letter that is showing. Green light on C means the string is tuned to C.
If the guitar sounds IN TUNE
- Your tuner is messed up and displaying the wrong notes even though it is in tune
- Your tuner might have the ability to tune to different modes/presets. You might have this option selected and be tuning to a different tuning other than "Standard tuning" which you should be tuning to.