First of all, you will need to go to a domain name provider and buy a domain name from them (i.e. eNom, Godaddy, 123reg, etc).
After buying the domain name, they will give you access to edit its settings.
Every domain name provider may have different naming conventions, but you will need to search for something called DNS settings / Host records / DNS records, or similar.
If you want to point the WWW subdomain to your website (i.e. www.mydomain.com), add a CNAME record, set the host to ‘www’, and point to the correct address. This address can be found by going to Site settings > Domain mapping > Map a domain.
If you want to point the naked domain to your website (i.e. mydomain.com), add an A record, set the host to ‘@’, and point to the correct address. This address can be found by going to Site settings > Domain mapping > Map a domain.
Map the domain name to the site
After adding these records, go to Settings in the eCommerce Store Builder.
Click on the Domain name option, and then click on Map a domain.
- Type the domain name into the Domain to map field
- Click on Test mapping
- Click on Map domain