How do I use MoonPay to buy Crypto?

Hello there, could you please elaborate on the process of using MoonPay to purchase cryptocurrency? I'm particularly interested in the steps I need to follow to get started and any potential challenges or considerations I should be aware of. Additionally, is there a specific type of cryptocurrency that MoonPay specializes in, or can I buy a wide range of digital assets through their platform? Thank you in advance for your guidance.