Warping to the Entralink will send you into a field. If you go North, you'll find the entrance to Entree Forest. If you collected and chose to send over items from your last Dream World visit, you'll find a little boy here who gives them to you.

Once you go into the Entree Forest, you'll find the Pokemon you interacted with in the Dream World. Talking to them will give you the option to capture them. You'll have a special ball in your bag - a Dream Ball - to catch them with. It has a handy 100% capture rate, but you can also opt to use your regular Poke balls if you'd prefer.

The Entree itself is found within the Dream World, the large, lone tree that lets you select your Pokemon to bring back in exchange for one berry.

There are other parts of the Forest, but as of yet we aren't sure if they have any special features.