Where is referral code found?

Excuse me, could you please clarify for me where exactly I might find the referral code that I need? I'm having some difficulty locating it and I'm not sure if it's supposed to be within my account settings, in an email from you, or perhaps on a specific webpage. I would greatly appreciate any guidance you could provide to help me locate this referral code as soon as possible. Thank you in advance for your assistance.