Here's how you install Mida script on your Magento or Magento 2 site:
Log in to your Magento admin panel.
From the main navigation bar, select Stores » Configuration.
Next, select the Design option in the sidebar menu. If collapsed, expand the HTML Head section.
Paste your Mida snippet (where to find my Mida snippet) in the Miscellaneous Scripts text box. Next, click Save Config.
Congratulations, you have installed the Mida tracking code!
Refresh Cache
You might spot a message that says: "One or more of the Cache Types are invalidated: Configuration. Please go to Cache Management and refresh cache types". Don't worry, just go to Cache Management. Look for Configuration on the list and hit 'Refresh' submit. That's it - your Configuration should now be up and running!