Hewston the Pug

"Hewston, we have a problem: Who ate all the cheese?"

Where to find Hewston after installing the sticker pack...

Open up a message and tap the ">" button

Then tap the App button (it looks like an A)

Next, look in the lower left part of your screen for the button with the 4 circles and tap this to open your iMessage sticker app drawer

Hewston should pop up wearing 3D glasses.  Tap the icon to start using the stickers.  Enjoy!