Easy answer- Find the goldfish a nice goldfish pond to live in.
Not so easy, expensive answer- You will need all of the following:
20+ gallon aquarium (no less)
40 gallon filter
water conditioner
substrate
goldfish sinking pellets
gravel siphon
~A healthy fish will be alright without food for a week, but without maintaining water quality, the fish may not last that long. Do you at least have water conditioner?