You call your bank and they give you the forward rate for July 15 delivery which is 0.85 SFr per DM

Then you enter into a forward contract with your bank, specifying that you will - on July15 - receive DM 500,000 in exchange for SFr 425,000. (DM 500,000 x 0.85 SFr/DM = SFr 425,000)

May 1: You purchase a DM 500,000 forward contract for July 15 delivery at a forward rate of 0.85 SFr/DM