How do you get Moonriver on MetaMask?

Hey there, I'm curious about how one would acquire Moonriver tokens and store them in their MetaMask wallet. Could you walk me through the process step-by-step? Is there a specific exchange or marketplace I should be using to purchase Moonriver, and are there any additional steps I need to take to ensure the tokens are safely stored in my MetaMask account? I'm new to the world of cryptocurrency and would appreciate any guidance you can provide.