The first time you turn your device , it'll walk you through the steps to get it setup. You'll be prompted to do the following:
If you use Gmail, you have a Google Account. Just use the same email address and password to sign in here. By signing in, all of your email, contacts, calendar events, and other data associated with that account will be synced to your phone. If you have more than one Google Account, you can add them later.
If you don't have a Google Account, you can create one during the setup process. You can also skip this step and create one later. To create a new Google Account, go to the Create your Google Account page.