Hi Gino,
You have posted in the MoodleCloud forum, however this question isn't specific to MoodleCloud.
You can add user profile fields to your users, please see the following link for more information: https://docs.moodle.org/en/User_profile_fields
I hope this helps.
Many thanks.
(Edited by Mary Cooch to clarify docs link- original submission Friday, 8 June 2018, 6:17 AM)