There are a lot of musical instruments you can play in Black Desert. One of them is Drum.
First you need to rent the drum from the Choir Leader for 2 CP (you get the CP back after your return the drum).
Once you've rented the drum, right click on it to equip it on the Main Weapon slot. Once equipped, press spacebar to start playing. You will see 5 collumns appear above your character with 1 glowing collumn, where notes are falling on each collumn. Press L and R to move the lit collumn and avoid being hit by the notes. Your character will also walk while playing the instrument.
If you do get hit by the notes, your character will stop walking. But don't worry, you can just press L or R again to start where you left off.
Once you're done using the drum. You can go back to the Choir Leader and return it, he will inturn return your CP.
So there you have it, hope you'll find this useful!