In this folder the skin files could be placed according the next file naming convention
character_[number].png - Public skin, available for all users
character_[name].png - Public skin, but named as "name" - usefull to enhance already provided skins like sam
player_[nick].png or player_[nick]_[number].png - one or multiple private skins for player "nick"
*_preview.png - Preview files for public and private skins - Optional, overrides the generated preview