How to Create an Event in Google Analytics

How do I create an event to know how many clicks it had on my site video that is inside an iframe?

For example:

<iframe width="100%" height="480" src="https://www.youtube.com/embed/-_J9rlkd1Yc?rel=0&amp;controls=0&amp;showinfo=0"frameborder="0" allowfullscreen>
</iframe>

Where do I enter the ga code?