Custom Post Types
You need to create a page for the portfolio, so go on Pages -> "add new" and create a page with the "Portfolio page" page template. This custom page template will display all the Works custom post type entries.
The Works custom post type comes with a custom taxonomy named Type; each type of work inserted corresponds to a menu voice in the Portfolio page filter menu.
The Works custom post type also supports videos. If you want to link to a video, paste its URL in the ‘Video URL’ custom field.
In the Testimonials custom post type you can use the title as testimonial name, the excerpt for the message and the extra custom field "company" for the testimonial company or some extra information.