what do you mean black to earth? black on the battery is earth (usually)

look at the signs on the battery

+ = positive
_ = negative

so + - + and _ - _ and you wont go wrong


dont worry if it sparks slightly when you connect the last one, it just means their is a good connection, give them a little shoogle once their on to makesure the connection is good as dirt/grease can give it a bad one.

Makesure they + wires and the _ wires dont touch each other

You could also connect the earth wire on the dead battery car to an engine lift eye or something simmilar

If it doesnt go on the first turn of the key, leave the ignition on and give it 5 mins (dunno what this does but works for me?)