When I am sending messages to some people the bubble is green and many times I get a red notice it was "not delivered" Why?

If you can’t use iMessage (which happens, for example, when a recipient isn’t using an Apple device), you can use SMS/MMS. Messages sent with SMS/MMS appear in green bubbles. For more information, see the Apple Support article What is the difference between iMessage and SMS/MMS? If message can’t be sent, an alert appears. Tap the alert to try sending the message again. There might be an issue with your cellular connection. See Send and reply to messages on iPhone - Apple Support.

...other then they don't have iPhones

If you are sending from the Macbook Air in your equipment line to people without Apple devices, you need to have the Macbook Air shown and selected in your iPhone under Settings > Messages > Text Message Forwarding:

See:

Forward SMS/MMS text messages from your iPhone to your Mac or iPad - Apple Support