COPY YOUR STICKER FROM THE GIPHY APP
Now for the magic! Before you post that story, Open up the Giphy app and find your desired sticker. Again, favoriting your stickers is the best idea if you want to access them quickly on the go. Just navigate to your favorites, find the sticker, and tap the sticker to copy.
Once it's copied, open up Instagram again. You'll see your story now has a little banner showing the sticker you copied from giphy! Touch the banner and your sticker is on your Story! Batta Bing Batta BOOM!