The Testimonial is part of the TheBizco theme. You can setup it very easily. Here are steps.
To setup Testimonials, first you need to add some entries with photos and texts. Go to "Testimonials" section and click "Add New". Fill details as described in below screenshot:
Create some more entries as described above.
Now we need to create a new page to show our Testimonials. The option is included in "Visual Composer" plugin (Make sure you installed Visual Composer plugin). Go to Pages >> Add New and click on "Add element" button:
You will see all Visual Composer elements. Click on ThemetechMount Testimonial Box option:
Now you will see options for the Testimonial area. Just modify the option are your requirements and click on "Save" button to apply the changes:
The Testimonials box is inserted. The box will look like this: