First take the supplied grip strip and place it under the base board.  Remove the first fillet by placing the fish on the base board with the spine facing away from you.  Open the gill flap of the fish and slide it back onto the bracket. Remove the first side fillet by slicing behind the gill flap and pectoral fin through to the backbone.  Turn the knife blade 90 degrees and slice toward the tail along the spine (preferably with an electric fillet knife). Place one or two 3/8" upper boards over the posts through holes as determined by the size of the fish being filleted to continue with the second side. Place the fish with the flesh side down and the spine facing you into the cutout of the upper boards and remove the second fillet. You should wind up with two even fillets with minimal wasted flesh. Wash in warm to cool soapy water and store flat. If the boards warp over time, run hot water over both sides of the board, flex it and lay it on a flat surface.