Need help with website subdomain

I have a completely built out an e-commerce site on shopify, let’s call it “shopsite.”

I have a completely finished regular site.. let’s call it “mainsite”

I want to create a subdomain on mainsite called “shop.mainsite.com” I want the shop.mainsite.com subdomain to be the “shopsite” content without having to rebuild the site.

I think normally all I would do is update the domain name on “shopsite”; however I do need that to stay the same on its own. Essentially I need a clone of the shopify “shopsite” to be the subdomain shop.mainsite.com it’s important the address that shows is shop.mainsite.com

Sorry if that’s confusing. I don’t know how exactly to do this. If anyone can help I would greatly appreciate it

take the backup of you main site, and upload to your subdomain.

1. Add your sub-domain to Shopify under Settings > Domains - You'll add shop.mainsite.com there.
2. Create a CNAME record at your web host (If you're using cPanel, it'll be under Zone Editor) The name of this CNAME record will be shop and the destination will be shopsite.myshopify.com
3. Go back to Settings > Domains and click on "Verify Connection".

It'll take a few hours and it'll be done.

Once verified, your shopify store will be accessible at shop.mainsite.com