As with Fortnite challenges in past seasons, the hardest part of the new challenge is finding the letter. Finding it is also doubly-difficult, when you consider the map is entirely new. The good news is that if you look closely in the loading screen, you can see the letter "F" sitting on a hilltop in the distance, to the right of the three characters on the screen.
The letter is sitting near Lazy Lake, the image below shows the character standing in front of the letter and the approximate location on the map. The letter "F" doesn't look all that much like a letter to us but hey, stranger things have happened in Fortnite we suppose. It looks more like a wrinkled sheet of paper from most angles.
Once you find that letter, you interact with it to collect it and complete the challenge. Completing the challenge will win you 14,000 season XP. Each week a new letter will be out there to find. If you are only a casual Fortnite player, you can learn more about all the goings-on that led to Chapter 2. Fortnite Chapter 2 has new gameplay, vehicles, and a revamped battle pass. Other new features include new boats, pogo sticks, and new emotes for getting your dance on.