First make sure you have the latest version of the Facebook app. Then when writing a post tap and hold the globe symbol in the lower left corner of your normal keyboard and choose the Football Emojis keyboard (Football Emojis, Team Brazil, Team Portugal or Team England). When the Football Emojis keyboard is selected, tap and hold the sticker you want to use, when the size select menu appears choose the XL size. Finally tap into the message field and choose paste. Since Facebook stretch the stickers to a predefined size we recommend only using the XL size stickers.