Further Update, I know how to start up the engine, but I can't actually fly, like control the throttle, go forwards/higher, etc.
Viewing post in Hijong Park's Defender Patrol comments
you can fly by controlling collective and cyclic simultaneously.
If you want to fly up, you need to increase collective while adjusting cyclic to maintain 0 pitch and roll degree.
To fly forward, you need to control cyclic to find and maintain the pitch angle (usually between 15~20 degree pitch down) where the helicopter flies straight forward, watching vertical speed indicator. then you can slightly move the pitch around in case you want to fly up or down while flying forward