Hey, newbie, go to page one of electric training and scroll down to the line with the link to the "free flight simulator". You can set it up easily with an inexpensive two stick joystic and make it work like any transmitter to fly. I paid arount $12.00 for mine at Best buy, and it plugs into the usb on any computer. I advise using windows xp, but I'm sure it will work fine with which ever recommended version you download. It works very well, and the best part is it is another of those much needed savings in the somewhat spendy hobby of r/c flying. Good luck and good flying.
By the way, the decathalon has shorter wings and you may want to slap on the j3 wing for your first flights to enable better lift. The wing is about the only difference in the parkzone j3 and decathalon, anyway. If it is a bit slow, then search the threads here to find the pitch of prop that is recommended for better speed, but may use more juice from battery. You may also want to get the higher MiAh battery to use with same 8.4 volt ESC for longer flight. Watch for hot batteries near end of flight, too much heat and plastic don't mix well. Make sure you tape on a ribbon to battery pack for easy removal after flight, I pulled on wires to remove mine and later testing the motor, the battery wires caused too much heat from shorting in tha battery pack and melted wires all the way to the ESC and overheated it - fried. Just a note, if you decide to go to the nickel poly packs search the web for the explosion videos of these if not treated properly. I hope this only encourages you to keep going with electric, it's food for the flight-hungry, and more convenient than builing for a week, then flying. Have fun flying.