Copy all the files to your themes root directory and it should look something like this:
/wp-content/themes/my-theme/bbpress-functions.php
/wp-content/themes/my-theme/bbpress
/wp-content/themes/my-theme/css(Where ‘my-theme’ is the name of your theme, there is nothing you need to activate.)
Now I am *really* confused! Because the file I downloaded for this theme is called “default”, and none of those files are in it 