A dog is a big responsibility to care for. If your dog is a male you might want to get it neutered. If its a female you might want it to get it speyed if you dont want it to have puppies.
Most dogs enjoy going for walks so buy it a dog leash.
Dogs also enjoy to go for runs in the park, but make sure it is trained so it doesnt go biting people. You could buy dog toys for your dog. You can get toy bones, rope and balls and lots more. A dog should get two to three meals a day. You might want to buy dog rolls, jelly meat, raw meat and dog biscuits.