Here you can learn how to read music.
Free music theory lessons online.

This site is for UK music terms.
If you want to learn American (US) music terms, then go to:
http://www.music4musicians.com/minute_a_day_music_theory.htm

G A B C D E F# G
The scale of G major is G, A, B, C, D, E, F sharp,(#) G.

Tone, tone, semitone (B to C), tone, tone, tone,
semitone (F sharp to G).

D E F# G A B C# D
The scale of D major is D, E, F sharp (#), G, A, B, C sharp (#),
D.

Tone, tone, semitone (F# to G), tone, tone, tone,
semitone (C sharp to D).