To accept an offer received for a NFT:
1) Go to “My Assets” by hovering on your username/wallet address on the top right corner. Click on the “Orders Received” tab, and you'll see the list of all the orders you've received.
2) Click on the icon of the NFT you'd like to sell. That will take you to the item's page
3) Find the offer you want to accept and click on "Sell"
4) Approve the steps and sign the transactions in your wallet. You will directly receive the funds (minus gas fees, platform fees and royalty fees - if applicable)