For information on preparations to get to this step checkout the How do I redeem my Ada? section.
If you didn't manually went through the vending process via the AVVM, then this is most likely the kind of vending certificate you have.
- Enter the Force vended tab
- Select the wallet you want to redeem to and enter the password
- Uploaded the vending certificate via the Click to upload box
- Enter the email address you received the vending certificate at, along with the Ada amount and the Ada passcode in the pop-up dialog
- Click the Redeem your Ada button on the bottom