3D animation question

I am completly new to loading 3D files and animating them. What file format should I learn first. And what one should I learn to be able to animate a character with 2 animations at a time. For example, running and scratching his head at the same time. I think this has somthing to do with IK ( I dont understand that either (= )

any links to good sites with information would be helpful too. Thanks.

I think you should start with the wavefront/maya obj format first. It is in ascii format and easy to understand. I dont know about your animation question though