You need a small game license, a state migratory bird endorsements and a federal duck stamp. The federal duck stamp is an actual stamp that will be placed on the back of your license which needs to be signed across the face of it. Only required if over 15 years of age. The goose authorization is required only if you are hunting in the dusky zone 2A / 2B.
As for the duck stamp, they usually pick an artist print and it's kind of a big deal if you get one of your prints selected as the stamp of the year. Each year it's different dating back to the 30's. If you hunt sea ducks in Western Washington, you are required to get a sea duck harvest report card.
The main cards required are
2A/2B - Goose
Brant Harvest card
Snow goose harvest card
Sea Duck harvest card
Read the regs, if you have additional questions throw them out. I would encourage you to take the goose ID course. It seems pointless and a waste of time to most, but you only get out of the sport what you put into it. Birds can be a challenge for new shooters, so if you can get some additional help, why not. You will be that much more knowledgeable.