Programs and File Types--Help

1st of all, what would I use to convert ms3d (milkshape 3d files) to mdl, mdx, blp (and back to ms3d also)? Also, how do I use Mdls, Mdxs, and Blps in a map? What extension is for what purpose? Help appreciated!

MDX - Compressed model file. Warcraft reads them. Can be converted to MDL.
MDL - Model file in the form that people can understand and edit. More space needed. Can be converted to MDX.
BLP - Blizzard picture. Is required to color a model.

To convert from ms3d to MDL, use this. To convert from MDL to MDX, use this. To get MDXs into Milkshape, use Biturn (you'll have to search).

To use MDXs and BLPs in your map, open the import manager, import the files, set the paths to what the readme says, save, and restart the WE.

Will this program enable me to turn MDL into MS3D? Because I want to import the units into it and then create a skeleton for it. And thanks for the extension info!