Below are two links (one for Mac and one for Windows) for free downloads of programs that you can use to open the files in the "Administration" section in case your computer does not already have them. In most cases, for Windows anyway, WinZip can open the stuffed files.
 
FREE:
 
http://www.stuffit.com/expander/macindex.html 
 
http://www.stuffit.com/expander/winindex.html 
 
 
 
Read more about it at these links:
 
 
http://www.aladdinsys.com/downloads/ 
Expander 
Award-winning Expander gives you access to virtually any file you download
from the Internet, receive in your email or get from Mac, PC, or Unix
machines. The total cross-platform expansion solution
 
http://www.stuffit.com/expander/index.html 
Free and easy access to files, downloads and attachments!
 
StuffIt Expander easily expands and decodes all those files you download
from the Web or receive in your email. It quickly accesses StuffIt  files,
unzips zip files created by WinZip® and other zip utilities, plus
decompresses tar, gzip and bzip files for Unix users. Just drag, drop, and
you're done! Expander works seamlessly with Web browsers such as Internet
Explorer  and Netscape . From BinHex to zip, StuffIt to MIME, Expander
accesses more formats, in less time, with zero hassles.