How do you play the musical instrument baritune?
If you are referring to the stringed instrument that is anatomically similar to a Viola, then you play it as a Viola
First, you get a musical instrument. Next, you learn to play the musical instrument. Then, you go to the music store and you purchase the sheet music for jingle bells. Then you sit down and work out how to play the piece, measure by measure. Then when people come in, you nonchalantly pick up your instrument and start playing. They are surprised.