How to buy Hemule MetaMask?

How can I go about purchasing Hemule using MetaMask? I'm a bit new to the world of cryptocurrency and am looking for a step-by-step guide on how to navigate the process. Are there any specific requirements or precautions I should be aware of before making a purchase? Additionally, could you please explain how MetaMask works and how it facilitates the buying process of Hemule or other cryptocurrencies? Your guidance would be greatly appreciated.