If you need support from Yola please contact us via firstname.lastname@example.org or make use of our live chat service! We are working on a new approach to community-based support and during this transition period we are not adding any new threads to this forum. Many thanks to everyone who has participated over the years and we look forward to unveiling a new peer-to-peer support system soon!
Anything added to your site needs to be added from inside the Sitebuilder, so it's not actually possible for your site visitor to add a testimonial directly to your site. What I would suggest is that you add a contact form to your site where your site visitor could write a testimonial and send it to you, then you can add it to the site. Here is a link with more information: Adding the Yola Form Widget.