If you are new to Salesforce, you will need to set up a domain. Most likely, your org already has a domain configured. If not, please follow these steps.
- Login into the Salesforce org as an Admin
- Click on the gear icon.
- Click on the Setup option, it will redirect the user to the next tab.
- Enter the Domain Name of your choice in the text box as shown in the below screenshot and click "check the availability" button.
- When the “Check availability” button turns green, click on the Register Domain button, and it will redirect to the next step.
Note: Salesforce takes a few of minutes to register the domain and the user will receive an Email notification when ready.