NW Format theme does not use the default style.css, rather it combines the small CSS footprint into the template.php for quicker page loads. Additionally, NW Format does not include a sidebar function. NW Format also includes a 2-column footer.
Unzip the nwformat.zip file and place the resulting folder in your /theme directory. Login to the /admin section of your GetSimple website, click the Theme tab, select "nwformat" from the dropdown and click Activate.