Each challenge you complete will unlock a slice of the birthday cosmetic set. Share your squad’s best birthday cake dance party with #Fortnite1st on Twitter, Instagram and Facebook.
- Deal 1,000 damage to opponents to unlock the Fortnite Birthday! Emoticon
- Dance at different birthday cakes to unlock the Happy Birthday! Spray
- Play 14 matches to unlock 5,000 XP.
- Complete all 3 challenges to earn the Birthday Cake Back Bling
Complete the Fortnite Birthday questline in Save the World and earn the Birthday Brigade Ramirez Hero! Earn tickets to spend on Birthday Llamas which can contain Heroes and weapons from every event this year (not including quest rewards).
Source: https://www.epicgames.com/fortnite/en-US/news/fortnite-1st-birthday