Doing a science project. NEEEED help. Like now. So yahhhh ;D?

Ok, so I'm doing a science project and we have to build a musical instrument. http://www.activitytv.com/779-make-thumb-piano <------------ I'm making this. I need to explain exactly how the sounds are made on my instrument and why the sounds are different. I also need to explain exactly how the sound waves travel in my instrument and what causes the sounds to be different. And I need to include scientific vocabulary such as pitch, loudness, waves, sound, medium, wavelength, frequency, etc… I have no clue how. SO PLEASE HELP. ASAP/: