Getting a domain name involves registering the name you want with an organisation called ICANN through a domain name registrar. For example, if you choose a name like "example.com", you will have to go to a registrar, pay a registration fee for that name. That will give you the right to the name for a year, and you will have to renew it annually for (usually) the same amount per annum.
Most common registrars
How to buy a domain name through Commerscale ?
1. Click on the "Store Settings" (3rd icon) located at the top left
2. Click on the "Domain Name" link on the left menu
3. You will be able to view "Domains" section on the screen
4. Click on the "Buy new domain" button located at the bottom right
5. Fill out all the "Domain to buy" field
6. Click on the "Check availability" button and if it's available, you can buy it at the price indicated