How to get xDai on MetaMask?

I'm a bit confused about the process of acquiring xDai tokens on MetaMask. Could you provide a step-by-step explanation for beginners? Specifically, I'm wondering if there's a need to add a custom network to MetaMask first. Also, are there any specific requirements or prerequisites I should be aware of before attempting this? Additionally, could you elaborate on the safest and most reliable methods to purchase xDai tokens, considering the current crypto market conditions? Any guidance would be greatly appreciated.