A Fingerbob is supplied rolled up from both ends, with the rolls meeting in the middle so it looks like two adjacent rings of tubular bandage, as pictured:
Place one ring of the fingerbob on the tip of your finger like this:
Roll that ring all the way down your finger to enclose your finger in the bandage:
Grip the other ring (the one you did not roll down in the previous step) and twist it round once or twice as if unscrewing a bottle cap:
Now roll that ring down your finger too. That’s it!