iMessage needs to be enabled to send this message?

Hi there Milly_dee,

Thanks for joining us in Apple Support Communities! We understand you're seeing an alert indicating iMessage needs to be enabled to send a message on your iPhone. We're glad you're here, and we can provide some guidance.

To begin, you'll want to follow the steps in these links to set up iMessage:

Set up Messages on iPhone

Add or remove your phone number in Messages or FaceTime

If you run into any issues, work through the suggestions here:

If you can't send or receive messages on your iPhone, iPad, or iPod touch

Let us know how it goes, and we'll take a closer look from there if needed.

Cheers!