Skill Stock is located inside a house in Dark Village. If you come to Dark Village via Captin Seadog, simply head right until you see a large, dark portal. The portal isn't where you have to go, but a house near it is. Simply double-click on the door of the house to enter.
Once inside the house, you can talk to Shadaren the mage for information on the history of the game. He also will offer to send items to the bank as you cannot take resources into Skill Stock. In a future update he will also allow you to spend Skill Points aquired from the minigame to buy rewards.
Also in the room is a pool of water which is the real entrance to the game. Simply click on it and you will be teleported to an information screen about the game. This information tells you what to do and how the game works. When you are ready, you can enter the game and begin your task of gathering as many supplies as you can within the time limit. You will see more information on the time limit, how you can maximize your time, etc. on the information page in game.
You can recieve several rewards from Skill Stock. After each game (which can last up to 30 minutes) you recieve 4 random rewards. Most of the rewards you get will be "minor rewards" such as gold coins, resources, and potions. However, if you're lucky, you can recieve a "major reward" as one (or more if you're really lucky!) of the 4 rewards. These rewards range from masks that change your appearance to items that can be useful in skills and more! You also get Skill Points that will be used later to buy items from a shop.
Please note that you need at least a certain amount of Skill Points to get the rare items and that there are different levels of rarity. Each level requires more Skill Points to be included in your chance of recieving a rare item. Overall, the chance of recieving a rare item at all is about 20% (one out of five games) but if you have more Skill Points, you can get larger variety of rare items.
Rarity 1 requires a mere 2,000 points (should be easy to get 2,000 points even if you only have level 1 skills)
Rarity 2 requres 5,000 points
Rarity 3 requires 10,000 points
Rarity 4 requires 15,000 points
Rarity 5 requires 18,500 points (there is only 1 item in this level!)
Also, as you gather your resources you recieve 1/4 of the normal expericence as well! You don't have to worry about banking, plus you get items that you can get nowhere else!