This 'guide' is meant specificly for simfiles that you're creating,
not those that you have downloaded.
Okay, first thing that needs to be done here, is to reproduce the folders used for Song/Simfile placement.
These should more or less be the folders in your StepMania folder.
Right now we're only focussing on one of them - Songs.
This is the basic folder structure that your groups on songs should be in.
In this image - Songs being the base directory,
VirInPro - Zyb being the group directory,
and Gorillaz - Dare being the simfile directory.
Group and Simfile directories may be named literally anything
excluding symbols which computers don't allow.
Within the Simfile folder, we need to start with two files - one being the song preferably in MP3 or OGG form, and the other being either a blank DWI file or a blank SM file.
The blank DWI and SM files are incredibly similar and have the only three tags that the files actually need to start with. For those of you who don't want to download the provided blanks, those tags would be:
DWI
#TITLE:;
#ARTIST:;
#BPM:;
SM
#TITLE:;
#ARTIST:;
#BPMS:0.000=;
These should be filled out in a manner such as...
#TITLE:That Song;
#ARTIST:That Band;
#BPM:123.456; or #BPMS:0.000=123.456;
Now StepMania will recognize your file and you can begin working on it in Edit mode.
Q: How do I find the BPM of songs?
There are a few methods for this. One of them is old fashion by ear with trial and error. Another is to use a simple BPM calculator such as the MixMeister BPM Analyzer, which is usually pretty close if not dead on, with some exceptions. For the insanely tricky songs whose BPM may be inconsistent or progressive, or if there are static intros, intermissions, or odd audio samples used in the song which can throw off a BPM calculator one would suggest using DDream Studio.
Q: What about other tags in the DWI or SM files?
That is all explained in Customizing Songs/Simfiles.