Create yourself a dummy mission you can use, I have one set up for just playing around and experimenting with things. Remember you'll need a ground unit in place to be able to use ground power and talk to your crew! Enjoy!
The mission editor is pretty easy to get along with and mostly self explanatory, but there are many really good guides from basic to advanced littering YouTube. Should only take you a few minutes to pick up the basics needed to add an aircraft to the base of your choice.