Press 'PLAY' : Click a key on the keyboard to make a sound or a note. The 'badly drawn hands' if you can't tell is claps. The drum is a snare drum and makes the sound one makes. If you're interested in how to mute the volume, you click the down arrow, and click the up arrow to turn it up. Press 'How to use' : This page will tell you all you need to know about how to use the simulator. All the information (other than the volume set up I think) is on that page. Extra fun: Try and follow the music!
Credits to myself for inspiring myself when I made a drum simulator (go to my profile to find that). This was fun and quite easy.