How do I animate a biped model from 3ds max using XNA framework or not necessarily the biped model, it could be any 3D model but how can I code the animation?
Simply export your annimation from 3DS Max to a file type by supproter "XNA" (fx, fbx, etc. ..) And import your annimation in your project xna with "importer". (see the sample in the use of Microsoft Skinned model annim sample).
Many existing tutorial to convert a model from 3ds Max to annimé xna .. Here is one: