It's a little easier to watch the video, so that's below, and here are the written steps:
Make sure you're already connected your TrainingPeaks ATHLETE account to your Velocity account. Here's an article that guides how to do that.
Once you SAVE a workout in the Velocity workout builder, you'll see a "TP" appear in the upper right corner below your initials.
When you click on the TP icon, you'll be asked to confirm that you want to push it to TrainingPeaks. Click Yes.
When you go to your athlete calendar in TrianingPeaks, you'll see the work out on that day - you may need to refresh your TP calendar.