On fi.google.com/account: Select “Give $60, get $60” from the side menu. Choose your preferred delivery method for your code. You can send your friend an email or copy the Fi referral code to send to them directly. Once you've sent out the invitation, you can come back to your account homepage to track the status of your referrals.
On the Fi app: Select “Give $60, get $60” under the “Home” tab.
If you received a Fi referral link, click on the link and you'll be taken to the Google Fi Wireless website where you can join Fi. Your referral code will be automatically applied to your purchase at checkout. You'll receive your credit after staying on Fi for 30 consecutive days and paying your first bill in full.
If you received a Fi referral code, go to fi.google.com and click the join now button at the top right corner of the page. On the checkout page (last step of the Fi sign up process), enter your referral code into the promo code box. You'll receive your credit after staying on Fi for 30 consecutive days and paying your first bill in full.