How do you hold a concertina?
Source: Wikipedia Hold the concertina by placing your fingers through the straps on both the sides and keep your thumb outside. Your right hand should be next to the air button if the concertina is right way up. You can adjust the straps accordingly so that your finger movement is not inhibited.
How do you hold an English concertina?
Hand position
all your fingers, your arms should form one line with the sides of the concertina. Avoid bending your wrists too much. The correct hand position: Thumb slightly bend, fingers rounded. In this picture the little finger is being used for (chord) playing.