Guitar Help Needed!! (Epiphone SG-310) (Tuning/Strings help please)?

Alright so I just got my first guitar. It's a beautiful Sg with all accessories needed. I plugged it up to the amp and learned Smoke On The Water (just the main riff) in about 15 minutes. It sounded amazing, with just the right amount of distortion. Then I decided it wold sound even better if I tuned it so I got out the tuner it came with and started trying. Then I broke the high e-string and I have no idea how to fix it. Also it now sounds more like a banjo than a guitar... :(. I guess I'm just asking if anyone has any pointers on anything to do with the strings, tuning, or tone. Hopefully one of my guitar-savvy friends can come over tomorrow and help me out. although I don't know if there is guitar savvy as they say they are. Any help is greatly aprecciated. :)