One of the Lantern Rite Tales in Genshin Impact will introduce you to the Illumiscreen. You can spin some lanterns to create a picture that is projected onto a screen. Get all the parts lined up correctly, and it will reveal a map.
On day one, the shape is shown above, a Glaze Lily. You can spin the lanterns as much as you want, so just ensure they match the image shown above and then you can go on a treasure hunt.
Three waypoints will appear on the map, showing you where to go. That part is easy, just travel to the nearest teleporter, then head for the waypoint. Where it gets a little awkward is that some of these might be tough to spot.
The first treasure chest is located near a waterfall, sitting on a rock all the way in the back. There are lots of Cryo Slimes around, so take them out, then grab the chest.
The second can be found down in a deep hole filled with spiders and more slimes. Kill all the enemies, then you can climb on top of the stone structure to grab the chest.
Finally, the last one is on an island in Dihua Marsh. Just swim out to the island, take out the Treasure Hoarders, and you are good to return to Liyue Harbor and finish up the quest.
Make sure you check in each day to see if there is a new Illumiscreen Puzzle to get more treasure including artifacts, weapons, and Primogems.