Hi alison, is it a black mains filter.If so,there is a metal plate at the back that screws to the machine.Connect the earth wires to this.(green/yellow)Look at the top,it should say from the left,4U,3U,2U,1U.
Connect the two blue wires to 4U and 3U. Connect the brown wires to 1U and 2U.
All the best.
Foxy, August 2008