• https://www.pokemon.com/us/account/pgl/signup/
• Once you get an account, start up your game and get on your character
• Press the "Internet" button on the bottom screen, Press the giant "Game Sync" Button. Let the game save and connect to the Nintendo Wi-fi
• Tuck in a pokemon of your choosing (for those with B2/W2, the pokemon type will influence aspects of the Dream World)
• After you pokemon has been tucked in, log in at the http://pokemon-gl.com and select "Pokemon Dream World"
• BIG NOTE!: You can only play for an hour per game (so if you have White and White2, you can play on the White card and then play the White 2 card). You can, however, delay being thrown out immediately by selecting "continue playing" on the bottom of the menu. Use this if you're finishing up Island of Dreams, the mini game section, to get a pokemon you find, along with other loose ends.

Once inside Dream World

• This is where you'll be growing berries, building a dream house and [censored]. http://bulbapedia.bulbagarden.net/wiki/Dream_World has a pretty good guide on it.
• You can become Dream Pals with those you trade with, or just randomly finding people in Dream World. This is mostly so that you can help your friends by watering the garden, and get them to go to your Join Avenue.
• You can get pokemon here and bring them into your game by going to "The Island of Dreams." The pokemon you tucked in WILL influence the mini-game area you go to in order to gain points and get Dream World pokemon (B2/W2 only). Most areas will be locked, and remain that way till you get a certain amount of points. The Bulbapedia link above will give you the specific. To capture dream pokemon, go to the "Island of Dreams" play all the minigames and so on. In addition, pokemon you play minigames with will be transferable, but if you don't play the minigame, you cannot. When you feel finished, make a wish at the tree at the very end of the Island of Dreams by sacrificing 1 berry. Once you have done this, all you need to do is hit the power button on the top right screen, and select the "prepare to wake up and leave DW."
• To send items you find in dream world, access your treasure box inside your home, and press "send" on the items you want to send.

How to acquire Dream World items and Pokemon

• After you're done with Dream World on your computer, go back to your game, and repeat steps 1-4 on the "How to access Dream World" guide. This will wake your pokemon up, put it back in its box, and materialize items and pokemon you got from Dream World
• Get back to the game and press "Wireless" on the bottom screen
• Press "Entralink" and you'll warp to the Entralink
• Go north in the area. You'll see a girl in a white dress next to a forest entrance, and a boy (if you received items from Dream World). Enter the forest and you'll see pokemon you received from Dream World. Interact with it and it'll "Battle" with you. You'll notice you have no pokemon or anything, just a bag and the option to run away. Press "Bag" and select "Dream Ball." You will instantly capture the pokemon, and it'll be sent to your box. Dream world pokemon have different abilities than in-game pokemon, and these abilities have a 40% chance to transfer to offspring, only if the pokemon is female.