Anyway, that bike you found probably is a scam. You will find them on craigslist a lot. After you establish contact the "owner" will give some sort of weird financial payment option, for instance through western union, or they will suggest using their own service etc.
Bottom line, chances are they will take your money and you will get no bike at all.
You are 16? I think it is awesome that you are riding this young, but PLEASE stay on the ninja. Its a perfect bike in a lot of ways for someone your age. Insurance, and running costs on a racebike etc are going to be ridiculous. I know they arent the "coolest" bikes out there BUT hell, its still quick, and unless my highschool experience was different, you are incredibly lucky that your dad lets you ride one anyway!(Mine wouldnt let me get one until I was on my own)
Even so, I'm 23, and still ride a GS500. Not a "super cool" bike but I love it. Also, its easy to maintain and a blast.(Girls dont know what bikes are what, so dont worry about that
)Good luck.
Kellan