This is the instructions to obtain your Yahoo ICAL web address. Click here if you are importing from Google Calendar instead.
1) Log into your Yahoo Calendar account.
2) On the left side click the right arrow next to your target Calendar right side click on Options then Share Calendar as shown..
3) In the resulting screen be sure Generate Links is clicked then ...
...if using Firefox browser select Copy Link Location.
5) Upon selecting Insert WinCalendar in Word or Excel, click in the Setup... button next to the Setup Google or Yahoo Calendar Data Option & paste in the above address under ICAL Address.
Note if your PC does not have internet access you can also import a static Yahoo Calendar ICAL data by saving the ICAL file to your a local drive & then instead entering the ICAL file name into the WinCalendar form.