Once you’ve set up and verified your account, explored and populated your wallet with tokens, you can connect your Metamask to Opensea
and buy NFTs !
Purchasing NFTs involves gas fees. Indeed, the Ethereum network requires gas to execute transactions. When you send tokens, interact with a contract, send ETH, or do anything else on the blockchain, you must pay for that computation. Refer to here
To avoid any issue during the purchasing process, please add 0.05-0.06 ETH to cover gas fees.