Click on the prompts to do different things. Wood Bridge = 8 wood Stone Bridge = 4 stone Wood Sword = 13 wood Stone Sword = 10 stone Gold Sword = 8 gold Ruby Sword = 5 rubies If you ask a villager to trade, you won't be able to see how much money you have, so be prepared. Ruby > Gold > Stone/Meat > Wood The dragon battle happens automatically unless you have both a sword and bow.
I dunno, Sky Block from Minecraft? If you find any glitches, please report them to me. No, the game is not explained pretty much at all, and that really isn't going to change.