While the basic gmax tutorials are useful, I'd recommend the specific-issue tutorials at the Freeflight Design Shop Tutorials Section  http://www.freeflightdesign.com

Specifically, there is a "Partial Animation Tutorial" by Lee Rosario, which should give you a heads up

http://www.freeflightdesign.com/tutorials/flapdemo.zip

A little advise.

Whenever you wish to start on tutorials [especially in regards to animations] go through them little by little.

Animations can seem easy in gmax, but once you have exported the model [ei: to test it in FS or CFS] things can go wrong. And it can be a pain in the butt when trying to figure out what went wrong.

Since this is about animations, I would also suggest reading the tip in FFDS [Free Flight Design Shop]regarding the dreaded "scale matrix errors", and the annoying "applied-scale" warnings that appear after you start attempting to export.