Kristina, did you read the instructions on the calendar? This would be one way to write a strong premise.

Identify the following:
(1) Protagonist(s). Who is(are) your main character(s)?
(2) Goal(s). What do they want?
(3) Conflict. What is keeping them from their goal?
(4) Antagonist(s). Who(what) is creating the conflict?

Ultimately, you're marketing your book, not your premise, so there are no hard-and-fast rules about what it should look like. The purpose of identifying your premise is to create a road map for yourself as you develop the plot. You should always keep the premise and theme in mind and not stray from them (or make a conscious decision to change them) while planning your story.

However, I found this article that may help answer your question:

How to structure a premise for stronger stories  

Enjoy. Be sure to let us know what you think.

Cheers,
Michelle