Tap the rhythm you see. In order to record your attempt, first click the RECORD button, then you will hear one measure of clicks in the given meter as preparation. Then tap the rhythm you see along with the metronome. You can use the "T" key on your keyboard (preferred), or click the TAP button. To practice, you can listen to the rhythm by clicking the play button. Each time you finish a recording, you will see feedback, if there are any issues with the rhythm you should record again before submitting.
After completing 5 questions, you will be taken to the feedback screen, where you can save your score, review any wrong answers, or start over.