I live in an Australian inner city apartment built in 2007. I want to attach a shelving unit to a wall but haven’t ever done this before, so I want to make sure to do it properly. I’m not sure exactly what the wall structure is, so I’d love to get some input from anybody that can help. I’ve taken off one of the electrical outlet covers and taken some photos; see attached. Can you tell much from this? What will be important when hanging up the shelving unit?