Wario World is split into four stages that were created by the Evil Black Jewel. Within each stage there are three levels - two open environments that end in a boss fight, and a third solitary boss fight. In the table of contents each stage is labeled in black, and the levels are split up completely for easy navigation.
Within each open environment level the walkthrough is split up with headers to help focus on collecting everything in a logical manner (since most of the game is linear, the walkthrough addresses things as you would normally come across them).
From the start of the game you'll have access to only the Courtyard of Treasure Square and Excitement Central's Greenhorn Forest. Since it's the beginning of the game, there's nothing in the Courtyard besides the locked Huge Treasure Chest, paths to run on, and several books that can be used to save your game.