HaloMods "Classic" Read-only Archive

ok when i downloaded a bunch of skins and tryied to put them in the map it said it can only take .dds files and all the file i downloaded r obj files. how do i convert the files into .dds

.obj Files are models. To open models, you use Milkshape. If you want .dds files, you will need to extract them from a tag called bitmaps, and you can find this tag in a map with almost any program.