If you want to see the mechanics in action or read the official notes, you can check out:
The update was a game-changer for RPG Tycoon, moving it away from a simple gold-based economy to a more complex resource management system. Key Features of the Update RPG.Tycoon.Supply.and.Demand.v1.4.9.rar
A new Trading Post allows you to sell surplus resources or buy what you're missing to survive. If you want to see the mechanics in