For our first Beta Weekend Event (April 27-29), home-world selection and world transfers will work just as they will when Guild Wars 2 launches.
When you log in to the game for the first time, you will have the opportunity to pick any available server, or home world. If you choose to select a home world that is in a different region from where you purchased your game, you will be logged out for a short period of time while your account is moved to your new region. Once you have selected a home world, all the characters you create will play on this world and will represent it in our world-versus-world (WvW) format.
While you can change your home world, there is a limit of one world transfer every seven days per account and a charge of 1,800 gems for each transfer. A world transfer moves all of your existing characters to your new home world. Any subsequent characters you create will also play in this new home world.