Contacts can be updated and managed via the "Student Info" section of a students profile. When creating or updating a contact, you will first need to select the type of contact (e-mail vs. phone vs. cell phone). At that time, you can also create a label, which is what will be used to identify that contact (i.e. Mom's work).
The selection of the flag "Can send messages to this contact" means that any automated (scheduled) communication for that student will be sent to that e-mail address. The contacts that have this selection will have an "A" next to the contact. Contacts without that selection can still receive e-mails when sent directly to that e-mail. The "Primary" flag is what determines what information will appear on all reports for that student. The primary contacts will have a "P" next to the contact. Only one primary can be selected for each contact type. These flags are represented next to each contact and can be changed at any time.
Don't forget to save your changes after making your updates!