The BNB chain (previously known as Binance Smart Chain-BSC) is an EVM-compatible chain meaning it can easily run with MetaMask. The first step of this tutorial is to set up a different BNB network on Metamask. Open Metamask, click on the Network you're currenlty on, then click on Add Network. Fill details as below:
Now that you're set up in MetaMask, you can browse any BNB dapps with ease. Each account on Ethereum also exists on BNB chain which means you can use the same addresses without issues on Ethereum and BNB.
To get started you'll need to get BNB chain native currency BNB, you can acquire it on PancakeSwap or most centralised exchanges. For the latter, you can transfer directly to your BNB address via the BNB blockchain. If you purchase BNB on the Ethereum blockchain or many other chain, you can cross to BNB using the bridge: