custom field functionality

Ok so i am not sure if i am able to get your question properly — so i am trying to list down what i understand.

1: You can create a custom post type (for testimonials) where your client/admin can fill out title/description/author name.
2: To be able to display them on specific pages – you can create a template file for example -testimonials.php
and call the standard WordPress loop to display the content + call this custom post type -where and how you would want to display it.

to know how to create a custom theme page http://codex.wordpress.org/Page_Templates

and to know more about how to create custom post type http://codex.wordpress.org/Post_Types

Hope it helps

tech