Gday vod, an airbrush is not hard to use at all. There's plenty of online tutorials, but it depends on what you plan on using it for. To use it to spray at helmets or parts of armour etc isn't hard at all, mix your paint and blast away. If you want to learn to go other stuff like portraits etc then it gets more complicated.is your airbrush single action or double?
Play with your airbrush using cheap paint, learn to mix it to the recommended thickness, I've heard people suggest try get paint to same consistency as milk......id say this is a rough guide. Paint consistency plays a lot into the enjoyment / frustration levels
Experiment with air pressure as well, an inline moisture trap is a good idea as well. Trigger control is very important on a double action ( I haven't used single in years) basically with a double action pressing down on the trigger fires air out of the end of the airbrush, pulling back releases paint.......small amount don't pull back much.....if you want lots of paint then pull right back.
Make sure you wear a painters mask, having an extraction fan is a bonus. Using some paints is very dangerous, some give of fumes very similar to cyanide gas, these are more the uerathane paints used in car industry......look after yourself
As for a real tutorial just YouTube airbrush tips, plenty on there, I don't know your skill levels or desires with art or how far you want to go
Online is plenty from airbrush courses, to tips on painting guitars etc. best guy I've seen is an Aussie called Daniel powers
Good luck playing with your airbrush