Today i will show you the VII note and a way to use it in a 12 bar blues progression

I IV V is the normal chord progression
G C D

but if you add a VII to any of the chords for example:

in the new progression...

G for 3 bars
then G7 (add F) 1 bar
C for 1 bar
then C7 (add B) 1 bar
G for 1 bars
then G7 (add F) 1 bar
D7 (add C) 1 bar
C7 (add B) 1 bar
G7 (add F) 1 bar
D for 1 bar

thats all for now