Download MetaMask (a crypto wallet in form of a browser extension) or TrustWallet (an app for your phone). After that you will have to add the Binance Smart Chain to your network-list.Click here for a step by step tutorial.
Buy BNB on an exchange (i.e. Binance, Kraken, Coinbase etc.). Transfer the tokens to your MetaMask wallet address. BEP-20 addresses start with a "0x"
Click here to head on over to PancakeSwap or use this address (contract will be announced soon) to select Swallow. Set the slippage tolerance to 11-13%.