Hello kcarlen;
If you are refering to gsd files, each certified Profibus I/O device should come with a floppy or a CD containing its specific file (or you should be able to download it from the manufacturer's website). The file will have an extension gsd, gse, gsg... where the third letter refers to the language used (d stands for default, English).
In Step7's HWConfig editor, under Tools, select "Install new gsd file" and point to the directory where it resides. Then select the new I/O device from the Hardware Catalog.
Hope this helps,
Daniel Chartier