Tips on using my MBP?

So I bought my rMBP about 3ish months ago, and I really like it. This is my first apple product to ever own however, so I don't really think I'm getting as much out of it as I can. I know the basic gestures but that's about it. I noticed that there's some "notification center" on the side, but I have no idea what that is. Does anyone have any good tips for a new apple user? Also, I have about $40 left from the gift card I got (thanks student pricing! :D), so if there are any good suggestions for apps that would be nice.

Sadly, I do not own an ipad or iphone. I have my Windows Phone which I love (I can love both companies okay? :P ), so I realize I won't be able to take full advantage of the "ecosystem" I guess.

Thanks!