On mobile devices, the + icon next to Contacts in the side menu allows you to create a new contact.
In desktop view, the Add Contact icon can be found in the left hand toolbar.
In the Add Contact menu, you’ll be asked for the name, description, primary language, and contact number(s) of the contact. The description will follow the contact as it’s shared with and transferred between staff members, so use it as a quick way to get the gist of a contact’s status. The primary language is what will be defaulted to for scheduled voice messages. Press Create to save your contact.