At first, select 'RUN' or 'SWIM' or 'SKATE'. Then push 'START/STOP' button. After 3-5 seconds RUN: 'Set' = interval( = 'BANG'. SWIM: 'Take your marks' = interval( = 'BANG'. SKATE: 'Ready' = interval( = 'BANG'. After the sound, push 'START/STOP' button as soon as possible.