How do I add a person to my messages app? Thank you, How do I add a person to my messages app? Thank you

Just adding(agree with meg): you add their email(apple id) or email they use for messages or a cell phone number(iPhone). Sending a message to either of those(as long as they have messages enabled in settings) will work. I have multiple contacts with an iPhone. Sending a message to a cell or email will both work. My mom for example has an iPad. We send messages back and forth. I send it to her emai(apple ID) when I create a message. She is saved under my contacts.

When creating a message, I hit the plus sign or start typing Mom and select that email(saved in my contact list).

You seem to understand correctly. You add them to contacts. They register for iMessage. No, what device they have or whether they have registered is not shown in Contacts.

Can you elaborate, please? As I understand it, recipients need to register and must be iPhone or ipad users. But this information doesn't show in Contacts

If the other person is not registered with iMessage, the message will not send. It won't tell you if they are registered of not. I'd try one, if it doesn't work, check with the person to see if the email is correct and they are registered with messages.

Messages app is linked to your Contacts app. Add it there.