For the record, the 2016 MacBook Air does not exist, it is most likely the 2015. Anyways, I have grand parents with an sbcglobal.net email address, so your in luck. What they do is they have yahoo.com as their home page, and login to the email through the website. You can also use the Mail application in the dock to do this for ease of use. I will have instructions for both below.
Using Yahoo.com:
1) go to Safari or the internet browser of choice
2)in the address bar at the top type in yahoo.com
3)in the top right corner it says sign in and go from there
Using the Mail App:
1) launch System Preferences the app looks like this:

2) go to Mail. Contacts, & Calendar

3) Click on Other on the right bottom

4) Then Add a Mail Account, then Create

5) Add all of your information into the the boxes and you should be good to go with E-Mail using Mail app (also a picture below)


<Edited by Host>