Entering a Google Adwords promotional code after you’ve entered your payment details is relatively easy, it’s just that the menu is hard to find — hence this blog post.
Once you’ve entered your payment information in Adwords go to “Billing” > “Billing Preferences”:
Then click “More actions” > “Apply a promotional code”:
Et voila! You’re done.
PS: I have some free Adwords promotional codes. Feel free to reach out if you’re interested in grabbing one :)