Get a feel for your power delivery first. I had one of those bikes a while ago, and depening on the mods/ condition of the top end/ conditon of the KIPS, it can vary alot. Keep your weight in the rear and crack 2nd from low speed. When you are comfortable with that, start shifting to third. Then learn to work your clutch. Hold the throttle wide open, and fan the clutch lever through the fricton zone. Pretty soon you'll be able to get it up in 4th or even 5th no prob., depending on the cond. of your bike. Speaking from experience, try this on grass or loose dirt first if possible (you will probably wheel out a few times). If you start to wheel out its hard to not panic, naturaly you will hold the throttle wide open. Remember to either roll off, pull the clutch in, or tap the rear brake. Practice will pay off. It's a valuable tecnique, almost nessicary for off-road, especially for racing. Eventualy it will come with experience. Just ride every chance you get, as long as you do this, life will be much more enjoyable despite your rate of success.
Have fun with it, its the greatest sport in the world,
-Nick