Domain names can be sold in two different ways:
Trustless auction system
Peer to peer
Domain names can be sold using an auction system. The owner of the domain can decide:
The minimum bid
The duration of the auction
Search for your domain or go to My Domains section and click on the Sell domain button, read the description and click on Next
Select the minimum bid and date at which you want the auction to end.
Confirm the details of the auction, click Confirm and then approve the transaction
If you own a domain you can sell the domain peer to peer by using the Transfer functionality to transfer the ownership to a third party.