What happens when I choose Stickers?

If you tap the Stickers button, you will be taken to the Sticker screen. Here you can browse various stickers that apply various perks (described in the top-right) when equipped.

Firstly, you can purchase and equip stickers by interacting with the buttons on the right. Once you own a sticker, you will see some numbers at the bottom (e.g. 49/1). The left number is how many stickers you own, and the right number is how many stickers you need to upgrade. If you have enough stickers, you can upgrade the sticker using Cash or Gold via the buttons on the right.

You can equip up to 4 different stickers at one time, and tapping the arrows beside the center image will change the sticker slot. Finally, you can boost the perks effect for a specific slot by tapping the + icon at the top, and then by tapping the Gold button to upgrade the slot.