How do I manually add a network to MetaMask?

Hello, I'm interested in expanding my cryptocurrency portfolio and have been using MetaMask as my wallet of choice. However, I've encountered a bit of a roadblock. I'm trying to manually add a new network to MetaMask, but I'm not entirely sure how to do it. Could you please guide me through the process step-by-step? I'd appreciate it if you could explain the process in a clear and concise manner, so I can understand it easily. Thank you in advance for your help!