King of Avalon almost always has one or two seasonal events being active. At this time the Independence Day Event is one of them. This guide explains how the event works.
During the duration of the event you receive Fireworks whenever you are harvesting the resource buildings in your city.
You do not have to do anything else as what you normally have to do anyway to get Fireworks items, just harvest your resource buildings.
This event does not give any rewards for gathering resources or slaying monsters.
You get your prizes by selecting the Fireworks items in your items and clicking Use. Prizes I have received include: Gold, 100 Dragon EXP, 10 Assault/Guardian Power, 30m VIP, 10 VIP Points, 100 Dragon Spirit EXP, 1k Food/Wood, 200 Iron, 50 Silver, Knucklebone, 5m Speedup, 60m Speedup, 2h Firm Defense, Materials (Animal Hide, Cerussite, Pine, Bronze, Galena, Horn, Fire Opal, Spider Silk), Stallion Stone (I), Air Stone (I).
There is not much to it, just do what you normally do and collect the extra prizes, the same as several seasonal events before. If you have any questions, or comments, let me know in the comment section.