Freed, I have no Idea where to get black worms on line. Here they are very common. Also there is no brand name for clams and squid, just go to a fish market or supermarket and buy some.
Neil, just put some worms in a shallow container about 2" deep awith an air stone. Don't put so much air that the worms can't stay on the bottom. Very little circulation is all you need. Put in 2 drops of Selcon for a portion of worms, that is about a ping pong ball size of worms. Feed them twice a day if you can. Pick them up in a small bunch with a tweezer and put them in fresh water to feed to the fish with your baster. Don't put the worm water in your tank. Change the worm water with tap water every few days. They will last indefinately at room temperature, try not to get them too hot. If it is hot, put in more circulation.
Paul