How do you play c sharp off the staff on clarinet?

To play C# off the staff on the clarinet, you will need to use the following fingering:

1. Use what fingering you would normally use for a B and place your index and middle finger of your right hand (as if placing a low Bb) and use your right index finger on one of the holes under your right pinky.

2. Take your left index off of the register key and cover the bottom hole.