Pokémon Black and White/Striaton City and The Dreamyard

Striaton City
As soon as you enter Striaton City turn left. If you carry on walking straight you will find a Poke Ball. Inside you will find an X Speed. Now you have this you can enter the on the first house on the right. Talk to the young man in this house and he will give you a Great Ball. This will be your first Great Ball, an essential Poké Ball in a trainers equipment. If you go to the Gym, there will be a man outside. You can not enter the Gym yet so walk away. Next to the Pokémon Center is the Trainers' School. Before you go there go to the North East of Striaton City. You are about to enter The Dreamyard

The Dreamyard
In The Dreamyard are two trainers, Lass Eri and Youngster Joey. Use these two to train up your Pokémon. Another thing to do while you are here is obtain a new Pokémon. There is a lady after Youngster Joey who will give you a new Pokémon dependent on the Pokémon you stared with. If you chose Snivy at the start then the lady will give you a Panpour, if you chose Tepig at the start then the lady will give you a Pansage and if you chose Oshawott at the start then the lady will give you a Pansear. There is more to do here but right now return to Striaton City.

Striaton City
Now you have been to The Dreamyard, you can enter the Trainers' School. While this can be done before you go to The Dreamyard, it is highly recommended you go after The Dreamyard, as at the board at the back of the room is Cheren. Talk to him and battle him. After defeating him, you may proceed to Striaton City Gym.