How do I get Testnet on MetaMask?

As a cryptocurrency enthusiast and investor, I'm often curious about the latest developments in the blockchain sphere. One such development that has piqued my interest is the use of Testnets for experimentation and testing of blockchain networks. MetaMask, being a popular Ethereum wallet and browser extension, enables users to interact with various decentralized applications. However, I'm somewhat confused about how to configure MetaMask to access Testnets. Could you elaborate on the steps required to set up and use a Testnet on MetaMask? I'm particularly interested in understanding how to add the necessary network details, obtain test tokens, and securely manage my transactions on the Testnet. Your insights would be greatly appreciated.