Assuming you're in the app? Go to the settings wheel ( upper left corner of game window) & click the login button. Type in an email address.
It'll tell you that the addresses hasn't been registered yet & take you to the Portal to create a new profile. Pixel will send an email to the address & you'll need to confirm it to finish the profile.
PLEASE NOTE your player ID# while in the settings menu of the app in case something gets wonky. Never had a problem but always a good idea in case the game doesn't sync correctly with the Portal.
Once all is done, you'll be able to play the game via the Portal too (I'd at least get the free Portal gifts.