Select "Market" to buy at the current price or "Limit" to set a specific price, and confirm your purchase.

Several major exchanges list Steem and allow for fiat-based purchases through their integrated payment systems:

If you prefer not to use a central exchange, you can buy USDT on a platform like WEEX and transfer it to a Web3 wallet (e.g., MetaMask). From there, connect to a DEX like or PancakeSwap to swap your USDT for Steem. Easy Guide to Buying STEEM Now - Binance