So far I haven't found a tutorial on using it for a vented speaker. Looking at horn tutorials may help. There may be another as well. The site lists a number of "programs" for different purposes box and other factors. It's name has gone awol at the moment but mentioned on a thread on popular audio design software. I recollect it included edge diffraction and appeared to include at least some box dimensions.
I also usually run Linux but windows is around but never used which makes me wonder why I paid for it.
WinISD has plenty of tutorials that are easy to follow the first time some one uses it. That seems to be unique.