There are 12 notes or tones in western music. Each note is 1/2 step apart, and together in sequence they make up the Chromatic Scale (blue and green notes below). The notes are named after the alphabet letters ABCDEFG. In between each named note (except BC and EF) there is note designated as sharp or flat. Whether that note is a sharp or a flat depends on the key in which the note lives. For example, the note between A and B is Bb in the key of F, but it is A# in the keys of B, F# and C# (see Circle of Fifths below). The sharps and flats chart to the left illustrates how a note can be both a sharp and a flat. The only intervals without a sharp or flat between them are BC and EF.
Illustrated on the neck below are the notes on the E and A strings. The green and blue notes are both Chromatic scales spanning one octave. It is important to learn these notes' positions on the neck. These strings and fret locations tell you where to play the barre chords illustrated on the Barre Chords page. We're using sharps on the E string and flats on the A string to represent the notes that fall between the alphabetic letters. Remember that C#=Db and D#=Eb. After the Octave (12 frets) the notes repeat.
If you wish to form a Bb Major barre chord using the low e string as the root note [(Bb) remember Bb = A#], then use the barre chord based on E and place your index finger, the "bar" of the chord, on the sixth fret (Bb). Strum all six strings and you are playing a Bb Major barre chord. If you wish to form a Bb Major chord on the A string, use the barre chord based on A and place your index finger across the first fret (Bb) to form the "bar." Memorize the positions of the notes on the E and A strings and you have your barre chord positions.