Ah... you asked for help on adding a model... not where to find the model which is an entirely different thing. I'd suggest looking on the Realflight forum pages first... and then if you can't find something there... do a google search. BTW... the Blade 120 S2 is a heli, not a plane and being specific and accurate in your terms when you ask or search is very important.
If all else fails and you don't find something... Select another smaller model Heli... it doesn't have to be exact to give you the experience you need to learn to fly, just close