Hi there, @Brant2bren. That will ultimately depend on how you completed the purchase. If you purchased as a guest, your discount code would have been emailed to you to apply at a later date. On the flip side if you purchased as a registered user (with an email & password) your discount can be found in your "StubHub Wallet." No code is needed for registered users.
If you've misplaced your guest email, we can definitely get your code to you! Send me a private message with your email address & zip/postal code. Hopefully that helps!