https://www.gamespot.com/articles/fortnite-birthday-celebration-offers-bonus-rewards/1100-6460578/

Fortnite is preparing to celebrate its first birthday with a limited-time event. Starting on July 24, you can complete a set of special quests to unlock birthday-themed cosmetics and an XP bonus. You'll just need to do some footwork to unlock the whole set.

As detailed on the official blog, you can complete three different challenges with their own rewards, and one meta-goal of completing all three. The rewards and associated challenges are: