The importer is a tool to generate items (static objects, dynamic objects, characters), and also to generate character or vehicle skins.
The source assets must be placed in sub folders of {maniaplanet_user_dir}/Work.
The corresponding imported files will be created in sub folders of {maniaplanet_user_dir} (whithout /Work)
for instance:
{maniaplanet_user_dir}\Work\Skins\Models\ArenaPlayer\Susu => {maniaplanet_user_dir}\Skins\Models\ArenaPlayer\Susu.zip
{maniaplanet_user_dir}\Work\Items\SMCommon\Pickups\Laser.Item.xml=>{maniaplanet_user_dir}\Items\SMCommon\Pickups\Laser.Item.gbx
{maniaplanet_user_dir}\Work\Items\Storm\Dolmen\DolmenHorizontalA.Item.xml => {maniaplanet_user_dir}\Items\Storm\Dolmen\Laser.DolmenHorizontalA.gbx
and so on.
See this page for more informations.