Ancient Chinese secret.
Okay not really. Do a search for some 3D softwares out there. There are many of them, and depending on any previous experience in 3D, one may suit you better than another. Check out
www.rhino3D.com,
www.softimage.com,
www.newtek.com, and
www.alias.com. I'm familiar with all those programs and they are all great. I have a preference towards XSI though.
E-mail me if you have any other questions, kris at carsbykris.com.
Kris