Where do you get dig in LeafGreen?

Once you beat the second gym leader (the water lady), north of the gym is a house and an officer standing next to it. Beat all the trainers on the bridge near that, and keep heading east. There is a house and a boy in there who is shaped like a Pokemon. Talk to him and help him by pressing on the computer in his house. After that, he will come out; talk to him again, and he will give you the S.S. Anne ticket. Go back to the house with the officer, go inside, go outside (toward north of the house), and you will see a rocket gun there. Beat him in a battle, and he will give you dig.