I need a 15-20 second FB ad for a new educational business.

I'm opening a new small business offering courses for writers. The business is "Classes for Writers." I want to run a 10-20 second FB advertisement video to introduce the business and make it sound professional and enticing. The goal is to attract writers, and wanna-be writers, to come watch a free lesson, and then sign up for a paid course. The courses are cheap, so I don't have a huge budget for this project, but I'm willing to spend a reasonable amount as a business investment.