how do i get the message icon back on my home page banner

As Messages is not one of the apps you can actually delete from your phone, it's still there. Go to the App Library (last page after the home pages), tap on the search box at the top of the page. Scroll down to Messages. Press and hold on the Messages icon. Select "Add to Home Screen". Once the app is on your home screen, you can press and hold on it and drag it to the dock.