The testimonial component is found on Landing Page and Basic Page Content Types.
When published, a testimonial looks like this if you only want to highlight a piece of text:
If you want to highlight both a piece of a quote, as well as the entire piece it was taken from then you can add a link as well and it would look like this:
You can make as many testimonials as you like on a page. When you are creating a landing page or basic page and want to add in testimonial, you do so in the page content part of the Landing or Basic Page content type by clicking on the arrow next to add child page tiles and the other page content types appear. You can then select add testimonial from the drop down menu. See below what it looks like:
Once you select Add testimonial, you then get the following input screen:
You will note in the input screen the name of the person, job title, quote and picture are all required. The url and link text are optional.
Once you have completed this section that is all you do as there is no individual 'Save' button for a component. Components are saved when you save the page.