In the main navigation, go to "Manage Project":
Then under your Properties tab, click "Add New":
Then create your account name and select the Google Analytics property that you'd like to be used for analysis. These Google Analytics accounts are pulled from the Google Analytics email that you connected during initial sign up.
Once you're done, click "Add Property" and you'll be prompted to approve the updated billing to your account:
Once you've approved the billing then your new property will be available in the main menu and insights will begin compiling.