Wix has a proper custom code panel, so this is a paste into a settings box rather than a file you edit. You cannot rewrite the underlying markup of a page on Wix, but you do not need to: the structured data goes in as its own block.
The custom code panel
Open your site dashboard and go to Settings, then Custom Code. It sits under the advanced settings rather than in the editor itself.
Add code, and paste the structured data in. Include the surrounding
<script>tags exactly as the Fix Pack gives them to you.Apply it to all pages, and choose Head as the placement. Head is what the check reads first, though see the note below if that option is not available to you.
Publish. Custom code does not appear on the live site until you publish, which catches people out more than anything else here.
Share previews, one page at a time
Wix builds a page’s share preview from its Title tag and Meta description, so writing those well is most of the job, and the titles guide for Wix shows where they are. What is left is usually the picture, set for your whole site or for one type of page under SEO & GEO, then SEO Settings, then Basics & social share.
If the scan names particular pages as missing their tags, give each block its own page.
Settings, then Custom Code, then Add Custom Code.
Paste the block for one page, and name the snippet after that page.
Under Add Code to Pages, choose Choose specific pages and pick the page the comment above the block names. Never All pages: share preview tags describe one page, and on every page they would give your whole site the same card.
Under Place Code in, choose Head, apply, and publish.
Custom code only works on a published site with a connected domain. If yours is not connected yet, set the picture in SEO Settings and leave the blocks until it is.
Business details
Wix writes a basic business description for your homepage from Settings, then Business Info: your business name, website address, logo and location. Fill those in first. It does not publish your phone number or your opening hours, and those are what the business details file adds.
Fill every capitalised slot in the file, or delete that line.
Add it with Add Custom Code as above, choosing your homepage under Choose specific pages and Head as the placement.
Publish, then check it with the Rich Results Test described below.
The viewport tag
You do not need to do anything for this one. Wix serves a mobile viewport on every site it builds, so if the scan flagged readability on a Wix site it is about something else, and the technical detail on the finding names which.
The footer contact block
Add a text element to your footer in the editor rather than pasting the HTML block. Type your business name, phone number and the towns you cover as ordinary text, and link the number so it dials on a phone. What the check wants is the details readable as text, not that particular markup.
Checking it worked
Publish, then load your homepage and view source and search for application/ld+json. Then run your address through Google's Rich Results Test.
If your screens do not look like this, the wording has moved rather than the setting. Search your platform for the words in bold above. If you still cannot find it, send us the scan link and we will tell you where it is on your setup.