Trung, Sean has answered your questions perfectly, but I will like to add a couple of things. For your safety, if you use the any plastic or fiber prop, which are very durable, dull the edges with sand paper because they cut like knives. I will recommend you use wood props for now, they break if they hit something, that alone might save you or somebodyelse a trip to the hospital. Taxing the airplane is very good for you as it teaches you many things, like engine/power control, engine adjustments, and taxing is the preamble to take off, so mastering that will help you later when flying. When you taxi, practice both going away and coming towards you, you will see that the orientation or motion reverses to your view, coming towards you, a left turn goes to your right, same will happen in flight with turns, keep that in mind and practice it. Remember to power down the throttle to idle ( or to off ) in any difficult situation, even in flight, it takes much practice to make power help you in an emergency. Please tell us what airplane you got to give you hints on it. Do not hesitate to e-mail Sean, or me, with ANY questions no matter how simple they sound. Good luck !!! <<[email protected]>>