s-1970-song-marley.jpgJacob Marley was Scrooge´s partner, companion and friend for a long time till he died on a Christmas day (seven years ago). Marley showed after his death to Scrooge as a Ghost. He was draped all over with a long chain. On the Chain were things like cash boxes, wallets and keys.
He is telling Scrooge that he have to wear this chain, because its the chain he made himself in life, its for not socializing and for being greedy after money. The chain is a symbol now, that he have to socialize and he cannot rest in peace. Marley is telling Scrooge that Scrooge have a chain like this too, and that its even longer. The Ghost is leaving Scrooge with the message that other Spirits will visit him soon.