Casanova, the preamble tells us that the grid consists of 42 two-by-two squares, so there effectively seven columns and six rows. The columns are notionally A to G (the last four leters of the hidden instruction).
Each two-by-two square must have a disc inside it, using two colours to distinguish the two plays. The moves simply follow the sequence of the specified letters from the spare words, all of which end in one of the letters from A to G.