Not really sure about panda3d, but I am pretty sure you need to start thinking about the algorithms and structure / pattern of making bones then moving them, then skinning them with your sprites.
Once these concepts are strong in your mind, you should then apply them to panda3d (what ever language / scripting it uses) or look up specific panda3d existing 2d animation systems using bones.
Similar to - how to learn 2d animation
