How to set up I message

Messages should already be on your iPhone. Look for this icon:

If it is not on your Home Page toolbar (bottom of window), or on any other page as you swipe right to left, you will find it in your Library page, the last page you reach when swiping. It has to be there, as I think you cannot delete it.

Please refer to Use Messages on your iPhone or iPad.

It is already on your phone, go to Settings > Messages and turn on iMessage.

I want IMessages does not work on my iPhone.