I'd like to help you, but I don't think it'd be a good ideaf or me to just go through the entire score and tell you what key every measure is in. For one, that'd take a lot of time, and it wouldn't teach you anything. Instead, I'm going to suggest you that you either ask your teacher to begin explaining theory to you, or you can undertake the task on your own. I had fairly sketchy knowledge of theory until I took a class in high school for one semester that gave me the basic knowledge that every pianist should have. You basically need to memorize the circle of thirds, in other words, knowing the order of all the keys, knowing which keys have sharps and which have flats, and how many, etc. You should memorize all the triads (C-E-G, D-F-A, etc...), you should learn about intervals, chords, and so on. From this knowledge, you can figure out what key a piece of music is in, you can figure out exactly what chords you're playing, how different chords relate to eachother, and get a better idea overall of what's going on with any piece of music.
You could very easily ask your piano teacher to explain it all to you, but that may not work, because music theory is quite a different subject to teaching piano, and it would require a decent amount of time. You could pick up a basic theory book, but it may be somewhat difficult to discipline yourself to learning all the required information. I think it would work best if you had available to you a course in theory, as I did. Are you in high school? college? If you are attending school, hopefully there is a music theory class available to you. The basics are actually fairly simple, once you get the hang of them, and they could make a reasonable amount of different in your piano education.