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 0x4A00bf6C94DFf744aea483894F58540cC8C1352f to select $BabyCakeDoge. Set the slippage tolerance to 15% (sometimes it may be a bit more, depending on how much demand there is)