Bone animation

Hey, Im using the milkshape 3d file format to load in models, with bone information, the only problem is, since ive never even seen/used bones before, i have no idea how to use the bone data in the file to deform the mesh. Basically i need a starting point to learn about bone animation, and also a little more info on how this info is stored in milkshape 3d files. Im not sure about things like, what rotx, roty, rotz are relative to, how to work out rotation of points, where to rotate from. Yeah, im pretty much in the dark about bone animation Any help would be greatly appreciated. Thanks -Mike