There are 4 theme specific blocks you can use. They are:
Posts Grid displays your latest posts or selected posts and pages. You can filter by category and display authoring details. More about the posts grid here.
A simple contact form with optional fields and autoresponder. The form options are all found in Dashboard > Settings > Contact From. More about the contact form here.
A form for your clients to add a testimonial. The testimonial settings are found in Dashboard > Testimonials > Settings
Display testimonials with featured images and links to project pages. More about testimonials here.
Some of the theme blocks have controls. For example, these are the controls for the posts grid block: