See how in step 1 it says to make sure you have a my-templates folder?
You’ll be putting style.css in /public_html/forum/my-templates/NEWTEMPLATE/
With a header in style.css like this:
Theme Name: The name of your cool new theme.
Theme URI: Your theme's url. Maybe it's the blog post you wrote about it.
Description: Describe your theme here. You can be nice and say something like "Blues and Greens in a two-column format" or enigmatic and say "The river here is only waist deep".
Version: Always number your releases. Please only use numbers and decimal points (yes, we broke our own rule).
Author: Author of the original theme,
Author URI: and his or her url.
Ported By: Name of the person who ported the theme to bbPress (if applicable),
Porter URI: and his or her url.