To add your Fotomerchant site as a subdomain to your existing website we will need to create 2 CNAME records in the DNS zone of your domain registrar account.
1) The first CNAME record will be the verification record -
[verification-code] - pointing to - domainverify.fotomerchant.com
This should allow you to complete the Domain Verification in the Website / Domain Name section of your account.
The Verification Code is the code provided by the Custom Website Address process and looks roughly like this: dvrdabcyair
2) The second CNAME record will be -
[subdomain] - pointing to - customerdomain.fotomerchant.com
Your Subdomain might something like "store" or "images" etc... your choice!
However this exact text should be entered for the target location: customerdomain.fotomerchant.com ..No substitution needed!
Note that when you go through the verification process in the Website / Domain Name section of your account, you can enter the subdomain name as well as your root domain name. Eg..subdomain.yourdomain.com
That should be it! As with all things DNS related, it may take up to 48 hours for these changes to take hold.. though it's generally much quicker!