If you don't know anything about music theory, and would like to get a nice foundation, then check this vid out.
The chromatic scale is the basis for all of Western Music. By western music, I'm referring to anything that descended from or was influenced by European Classical music.
It's a 12-tone system - CC#DD#EFF#GG#AA#BC
Above is the chromatic scale, and if you impose the WWHWWWH major scale pattern on that, you get a major scale. You can start on any note.
Below, the bold notes are the ones in the C major scale.
w w h w w w h
C C# D D# E F F# G G# A A# B C
So if we want to apply that do the note G, we get
G A B C D E F# G
and you can number each note. These are called scale degrees. So G is 1, A is 2, B is 3, and so on...
See the tab for how to apply this to your instrument!
We get chords by combining 2 or more notes. In bluegrass, the primary chords we are hearing are called triads.
A G major triad is G, B, and D notes played at the same time.
That is scale degrees 1, 3, and 5.
The tab will show you your different major chord shapes!