On Flag the guitar will do a scale. C will start the conga drum B will start the bass G will start the guitar. Note there is a D drum as well as a S singer, but they have not been coded to finish with the melody as I didn't love their sounds. Up arrow turns on the Conga drum, bass and electric guitars. Down arrow stops them.
This is my version of the Hour of Code Music tutorial i.e. following along from Make Music with Scratch: https://scratch.mit.edu/projects/editor/tip_bar=music&utm_source=codeorg