Login to your Defense.com account and click the Education icon on the navigation menu.
From the expanded menu select Training Campaigns.
Select View on the Training Campaign you wish to add a user to.
Scroll down to Campaign Users and click Add Users.
Click the Select Users dropdown and select any users you wish to add to the campaign.
Click Add Users and the users will be added to the campaign.
And that's it! You've successfully added a user to an active training campaign. 🎉