[(.Aztec);]

Yes, it does have to do with scriptfiles. You need to create or download a login and registration system, then under pInfo (the most commonly used variable), put pSkin, then create a /setskin command that SetPlayerSkin(playerid, skin); and then sets their variable, PlayerInfo[playerid][pSkin], then onplayerlogin make it set their skin.. SetPlayerSkin(playerid, PlayerInfo[playerid][pSkin]);