These are add-ons for StepMania. Many of these files are in the .smzip format. This format means that Stepmania will automatically extract the pack to the necessary  folder. If for some reason the file will not extract properly, or Stepmania doesn't recognize it, simply rename the extension to .zip, then extract to the folder stated in the descriptions.
Tutorial Name Description Download
DDR EXTREME Theme

An accurate DDR EXTREME theme for StepMania.
Extract this to: StepMania\Themes 

 Download
Koge2Steps Kanji Pack A Japanese Font Pack for StepMania.
Extract this to: StepMania\Themes\Default\Fonts		 Download
Koge2Steps Append 1 An add-on for the original Kanji Pack.
Extract this to: StepMania\Themes\Default\Fonts		 Download
Koge2Steps Append 2 An add-on for the original Kanji Pack.
Extract this to: StepMania\Themes\Default\Fonts		 Download
Arcade Note Skins Vivid and Solo arrows for 3rd, 5th, and EXTREME.
Extract this to: StepMania		 Download
Mantis Simfiles Banner A folder banner for your Mantis Simfiles folder.
Extract this to: StepMania\Songs\Mantis Simfiles		 Download