1. Login to your Website Panel via http://cp.domain.com.
2. Click Domains.
3. Click on the desired domain.
3. Select on Edit DNS zone records.
4. Select Add Record for new creation and kindly follow the below records to configure the DNS setting.
a) Point "blank" A record to 18.104.22.168
b) Point "www" CNAME to yourstorename.myshopify.com. Please note that yourstorename.myshopify.com is your myshopify.com subdomain.
5. Finally click on Save to save the changes and please allow few hours for the effect to take place.