You need to create a seperate folder for each mod.
Example:
You're willing to install a skin on maccer,
create a folder named maccer inside the modloader folder (can be any name as long as you recognize that it's the skin mod)
put the maccer.txd and maccer.dff in
Also, you have to check if you have automatic refresh on at the mod configuration.
Feeling freezes? Disable the first options in mod configuration:
