After meeting Professor Birch's child (your neighbor), you go north to Route 101 to find Professor Birch.
Help the Professor
As soon as you enter the route, you find Professor Birch calling for help. A pokémon is chasing him. Check on the professor's bag in front of you.
Choose Your Starter
When you look in the bag, you find three pokéballs, each of which contains a starter pokémon. You can choose Treecko, which is a grass-type pokémon; Torchic, which is a fire-type pokémon; or Mudkip, which is a water-type pokémon. Choose carefully, because you won't be able to change your choice afterward!
Battle the Pokémon
After you have chosen your starter pokémon, tap Fight in the touch screen, then choose one of the moves. If you want to learn about the moves, use the control pad or circle pad to put the cursor over a move, then hold L and press A to read information about the move. Or you can go tap Pokémon in the bottom right of the screen, choose your pokémon, then tap Check Moves.
Use attack moves against the opponent pokémon until you win.
Name your Pokémon
Afterward, Professor Birch will recognize that you're the child of his friend Norman (the gym leader of Petalburg Gym). Professor Birch will escort you to the lab. He'll tell you to keep the pokémon that you chose. He will give you the option to give your pokémon a nickname. You will be able to change this later on in the game if you want.
Professor Birch says that his child is in Route 103 and says you should go there. You can use the map (a.k.a. AreaNav) in the touch screen (the PokéNav Plus) to find Route 103.
Professor Birch says you can rest up at your house. Go talk to your Mom to heal up.
Tap the map in the touch screen and you will see that Oldale Town is to the north, and Route 103 is north of that. So, when you are ready, go north to Route 101.
Go Through the Route
You don't have any pokéballs right now, so you can't catch any wild pokémon. If you push the circle pad only a small amount, you will sneak quietly, so it will be less likely that you will encounter wild pokémon in the tall grass.
When you go north, you will find a ledge that you can't go up, so go to the right. After going through the grass on the east, go north and then northwest. There is a boy in the tall grass there who will give you some advice.
Go north from there and you will arrive in Oldale Town.