To access the County Fair event quests, tap the arrow button in the County Fair event area. The event consists of a sequence of nine quests as well as a challenge mode that unlocks after you have completed the quest sequence. Completing the quests will reward you with outfits, gems, and boosters.
Each completed quest will reward you also with horseshoes. You can see the horseshoe counter at the top of the quest sequence. The amount you have is displayed also below your lives counter in the upper left corner. After you complete a quest, the horseshoes from the quest will be added to the counter. When the amount of horseshoes you have collected reaches the gift boxes in the counter, you're able to claim the gifts and get the decorations for the County Fair area restored. Once the horseshoe counter is filled, you can claim the grand County Fair chest filled with amazing rewards. You can then also continue to the challenge mode that unlocks once the linear quest sequence has been completed.