Below the checkmark is a box, or rather to the left and down of the check mark is a blank space to type whatever your going to say and then it embeds it into the trailer. Whatever you say gets saved for future viewings by other people.
BTW, you can have plain white text, green text, blue text or red text. Look above the checkmark and click the box to choose your color.
AWESOME!, something else I just found out. By slececting the box to the immediate right of the green text box, you will be able to type in stationary text near the bottom. I'm loving this