How do I make a Sub-Event?

I know it's a dumb question, but I'm new (and therefore I am dumb). How do I make a sub-event, as I mentioned in the title? Thanks in advance for any help :)

Several ways:

* Right-click on the event that will be your top event and choose "Add sub-event" or "Add blank sub-event" from the Add rollout menu.

* While your top event is highlighted, use the keyboard shortcuts (B) for a blank event, (S) for a regular sub event.

* If you have an already existing event you want to make into a sub-event, highlight it then drag it under the other event. You should see a black line with an arrow pointing inward, under the event.

Thank you very much!