Hey dude I have had my ninja from new, like Rob said don't get to concerned, as long as your not thrashing it and red lining it you'll be fine, there are so many different opinions some say you should ride em hard in and others say ride em like miss daisy, what I say, just go easy you don't have to be over cautious but don't go thrashing it either. The ninja's rev pretty hi anyway so don't get freaked out if your sitting around the 6-7 rpms, you'll notice after about 1000km on it it gets a bit more power and that's when you can start giving it a bit more.
There are few others on here with the ninjas so they'll be able to give their input to.
Hey velcome though to the most awesome place and people in the universe.