How to find notes on my Casio?

I need a little help. My Casio piano model CTK-720 has no instructions or guidance on how to find the notes. There are tiny typed parts above a few keys on the piano itself, but they don't tell me where Middle C is. I would like for someone to help me by telling me where Middle C is on the 61 key piano. But if someone could tell me where the open G, D, A, and E keys are in treble clef on the piano then that would be best. I have read the manual several times, but it doesn't explain either. By the way, I need the open keys specifically because I have to fine tune my violin frequently. Any help would be greatly appreciated.