King of Avalon almost always has one or two seasonal events being active. At this time the St. George's Day Event is one of them. This guide explains how the event works.
During the duration of the event you get a chance of receiving St. George's Lances when slaying monsters and rallying Barbarian Camps, and Red Roses when gathering resources. These Lances and Roses show up in your inventory where you can use them to get prizes.
You do not have to do anything else as what you normally have to do anyway to get Lances, whenever you have Stamina you should kill Monsters or rally Barbarian Camps.
You have a chance at receiving Red Rose while gathering resources, which you will be doing a lot anyway, so nothing else needed to be done to get this item either.
You get your prizes by selecting the St. George's Lances in your items and clicking Use. Prizes I have received include: Gold, 100 Lord EXP, 100 Dragon EXP, 100 Dragon Spirit EXP, 500 Dragon Spirit EXP, 2500 Dragon Spirit EXP, 10 Assault/Guardian Power, 10 VIP Points, 30m VIP, 1K Food/Wood Items, 5m Speedups, 24 Hour Farm/Sawmill/Iron Mine Boost.
You get your prizes by selecting the Red Roses in your items and clicking Use. Prizes I have received include: 5K Food/Wood, Materials (Animal Hide, Bronze, Cerussite, Pine, Marble, Fire Opal, Spider Silk, Soul Clay), and Gems (Sentinel Gem (I), Stallion Stone (I)).
There is not much to it, just do what you normally do and collect the extra prizes. If you have any questions, or comments, let me know in the comment section.