To be able to add peers to widgets using your Google account you first need this peers to be in the contact list of your Google account. Since peers must login with their account to see shared widgets, only contacts referred to email prefixed by "gmail.com" are actually visible in the list of Google contact you can select from for sharing your widget with.
In the mail page of your account press on "Gmail" in the left upper side of the screen.
In the list that opened press "Contacts".
After that in the next page press on the blue "+" circular button in the right bottom side of the screen.
Enter the name of the new contact and press Enter.
For sharing using content glass widgets you must enter valid gmail address for this contact.
Other information about this contact is optional and is for you to decide to enter or not.
After finish press "save".
Then if you have a page with content glass opened with your Google user connected to you can open the social account view using the person icon on the button.
In the opened view click the refresh link in the Google row.
Continue to share widgets with your new contact.
For reference in Google site: https://support.google.com/mail/answer/8933?hl=en