Step 1. You need to login to your Admin control panel and click Set Up Software then Settings.

Step 2. At this click shows advance settings and click learn more beside the Integrate a registration form into your existing website.

Step 3. Click  integrate affiliate sign up page with my website.

Step 4. Create a new form.

Step 5. Complete the fields required.

Step 6. Copy the code and log in to your Shopify account.

Step 7. Click pages then Affiliate Program

Step 8. Show editor 

Step 9. Paste the code  the save