Pokemon black/white question?

how can i get dream world abilities on my pokemon? please indicate step by step how to get into the dream world and how to get my pokemon the ability. for example, i would like to have a drought ninetales and drizzle politoad, but how do i access the dream world and all that? i have wifi but do i need to make a special account or need a certain item? Thank you for the help and again, please be descriptive :)