From your base view, tap your Commander's picture in the top left corner. Once on the Profile page, tap the Settings icon in the bottom right corner. In the Settings popup, select Account to see your name, ID, Warzone location, and account registration options.
You can choose to bind your account via Facebook or Google, selecting either of these will walk you through the process step by step. Once complete you will be able to save and recover your progress, access your account on any device, or switch to another account.