**Select Palette:** Use the dropdown in section 1 to switch between preset palettes or select "Custom Palette (Edit Below)" to use your own definitions.
**Active Character:** Click a character in the **Character Pallet** to select it. The currently active character is displayed above the map.
**Editing:** Click any cell on the $24 \times 24$ grid to "paint" the active character onto that spot.
**Output:** The "Compiled Mapgen JSON" updates in real-time and includes both the **rows** array (the map) and your palette definitions.