Thank you! I was confused because I didn't know why they don't just draw a C on there.
Why do you play Moonlight sonata (which is very hard to play though) when you don't even know the basics?
I have been playing for 9 years. and am playing chopin etudes, and about just a year ago i figured out that if there is an accidental in a measure, it makes that note accidented for the whole measure.
you should take a look at some of alkan's music. it's terrible to read... double sharps and e# and b# everywhere!!!