Shopify keeps your site's HTML in your theme files. You add the Converly code to your theme's <head> once and it loads on every page of your store.
Step 1: Copy your install code
In Converly, click Install in the left sidebar and copy the code shown at the top. It is unique to your site. See Install Converly for the full walkthrough.
Step 2: Add it to your theme
In your Shopify admin, go to Online Store → Themes. On your live theme, click the ⋯ menu and choose Edit code. Open the theme.liquid layout file, find the <head> section near the top, paste your Converly code just before the closing </head> tag, then click Save.
Check it works
Submit a test entry through a form on your store, then open the Activity page in Converly. If the code is installed correctly, the event shows up there within a moment.
Apps that inject head code
If you would rather not edit theme code, most "header/footer code" apps from the Shopify App Store work too. Paste your Converly code into the app's head/header field instead.