I am having trouble putting my bike on its centerstand
Getting bike off of centerstand
It's safer to take it off while on the bike. The Ninja isn't too bad, but there are many stories of folks with heavier bikes dropping them while lowering them from the centerstand while standing next to the bike. It's good to get into the habit of sitting on it and rocking it off, instead of standing next to it.
Centerstand spring hint
Should your centerstand spring need replacing, here's how to get it back in place, without trying to use a pair of pliers, having said pliers slip off, and having the spring sail through the wall of the garage, or your foot.
It involves using pennies (and you thought they weren't good for anything...) Basically, you bend the spring sideways to open the coils, then stick pennies between them to keep them open. Sometimes you have to bend the spring back and forth, adding more than 1 penny to each slot. It takes some time, and can be a little fiddly, but it's pretty easy to do. Then, when you use the centerstand the first time, it'll stretch the spring longer than you have before, and all the pennies will fall out.