In order to add an affiliate program at your store follow these steps.
1. Log Into the Shopify app store and Install Affiliate application.
2. Go to the settings tab in the app and copy the link.
3. Navigate online store and click navigation option from the list. Select the main or footer menu option.
4. Select menu
5. Edit the existing menu then add the copied URL.
6. Save settings.
Previewing output –
When you click on the Affiliate program option, you will be redirected to the sign/login affiliate page.