I think we need more information about what you are trying to do..
Showing items on a map would consist of creating objects and setting their positions..
Without knowing how you place your objects in your layout it's impossible to say how you would get their information to display correctly on a map..
Example: The user playing the game in one map and in coordenate X , Y create one weapon to collect and this person use this weapon in the game. Understand?
Thank you for your help.
Por exemplo: O jogador está jogando o jogo em um mapa e em certa coordanada X,Y aparece uma arma para ele coletar, assim que ele coletar essa arma ele pode seleciona-la para usar no jogo. Conseguiu me entender?
Obrigado pela sua ajuda.