Hi ginasballoon – your site is running on WordPress.com so there’s no need to install Jetpack there as testimonials are already built right in.
Your dynamically generated testimonial page is at this URL:
http://ginasballoon.com/testimonial/
To set up Sela with testimonials on the front page, you’ll need to complete a few steps, including setting a static front page and assigning the Front Page template to it. You’ll find the full Sela setup guide here:
https://theme.wordpress.com/themes/sela/
These forums are for folks running the WordPress software on your own hosting, but your site is hosted over at WordPress.com. If you need further help with Sela for your WordPress.com site, please post in the forums there:
https://en.forums.wordpress.com/forum/themes
