So ...

You need to go to Testimonials -> Add Rotator to setup the carousel that will display the rotating testimonials on your website:

This is where you can define how your testimonials carousel to behave.

You can choose animation, duration for each testimonial, show/hide items, and more.

After that you need to enter the company or product that these testimonials are associated with. This information will not be displayed but will be used to add rich snippets meta data for search engines.

And lastly, you can select a theme for your carousel. By default, the plugin comes with two themes to choose from and you can purchase additional themes from the plugin author.

Once you are finished, just click the "Publish" button to save your changes.

And now that you've created the carousel, you can add some testimonials. That's the next step ...