How to change the login screen? .^,..,^.

guys can someone help me please i want to change the login screen for a dekaron p server.....you know when you need to enter your account name and password in the background you see a big door with phantom skulls coming out and all classes are in front of it.....how can i change that......like change the color of the door or make the phantom skulls red.or make them dance wear a costume......please would really appreciate your help ^-^.

its all in texture folder inside data. and if data is packed u gotta unpack it then repack it.

ok bro i understand that but i want the characters to wear a costume like swimsuit costume instead of the armour they are wearing:):).....someone told me its in data/mesh but i dont know the exact file or folder...think you can help me out ^-^