Replying to Computer help. Why is there so little space left on my hard drive?

So right now i have 5gbs of 215gbs left on my hard drive. Music and videos combined I only have 16gbs. I don't do anything but the internet, music/videos, and homework on my computer. Every folder in my Program Files takes up a combined 9gbs. I run system clean up and CCleaner and those both only take out a few hundred mbs. I know I'm not very computer smart but am I doing something wrong here? What is taking up all my space? Or is there something wrong with my computer?