How to Send Fireworks on Apple Messages

Open your iPhone's Messages. This is a green app with a white speech bubble on it.

Tap a conversation. Doing so will open it; if you'd prefer to begin a new conversation, you may instead tap the pencil-and-pad icon in the top-right corner of the screen and then type in a recipient's name. If Messages opens to a conversation that you don't want to use, first tap the "Back" arrow in the top-left corner of the screen to return to the "Messages" page.

Type in your message. Do so by tapping the text field near the bottom of the screen and using the on-screen keyboard.

Tap and hold down the blue "send" arrow. It's to the right of the text field. Doing so will open the effects screen. If this button is green, you or your recipient are using SMS messages, not Apple Messages.

Tap Screen. It's in the top-right side of the screen.

Swipe left four times. This will take you to the fireworks effect.

Tap the blue "send" arrow. Doing so will send your message. When your recipient opens the message, they will see a firework display behind your text.