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I checked your website http://www.jewelrysignatures.com/ and confirmed it's powered by Shopify.
You mentioned you're trying to add the Popup codes. I'm assuming you're referring to this:
Try the following in order to achieve that:
1. Go to your Shopify Admin Panel. Click "Blog & Pages" then click "Create a new page".
2. Enter your "Page Title" then click "View HTML" button and paste your code.
3. Click "Create Page", click "Navigation", click "Add Link", enter "Name of new link"
4. Choose "Page" for Links. Choose the page that you have created on the above steps.
5. Click "Add link" again to finish.
Related guide: Adding-a-form-to-Shopify-Store-Frontpage
Just click the link above to view the complete detailed guide. And ensure that you will use the Popup embed codes by following the screenshot I included on this reply.