You'll first need some Ether (ETH) to start bidding and purchasing NFT (Non-Fungible Token) art. Here are some exchanges that you can use to convert currency like USD, EUR, YEN, etc to ETH:
After you've created an account and funded it, you'll then need to transfer those funds off the exchange to a wallet under your control. Most wallets also provide a Web3 enabled browser to view the web and sign + broadcast transactions on the Ethereum blockchain. Actions like bidding, buying, or transferring NFTs are examples of transactions.