Download and Enjoy Knockout Stickers Pack. You can peel and place these stickers on anything in your conversation - bubbles, images or even other stickers.
How to Access Stickers in iMessage:
1. Open messages app
2. Compose a new message to anyone
2. Tap App Store icon in top left corner
3. Tap four circles icon in bottom left corner
4. Sticker Pack icon should appear in your iMessage App Drawer
5. If Stickers don’t appear, tap “Store" icon and then tap “Manage" tab to add sticker pack to iMessage Sticker Drawer