Science student12

Hello, I am a student attempting to do photography with Iron Salts and I have a problem. What exactly do these instructions mean? Mix 10 parts of ferrous oxalate (25% aqueous solution), 7 parts of concentrated ammonia solution, and 20 parts of a saturated solution of oxalic acid to produce a photosensitive iron complex. Prepare separately a 25% solution of potassium ferricyanide. Thanks.