All calendars are showing on my IPad but cant get scyn with Yahoo calendar on laptop.

Go to settings, mail contacts and calendars and under calendars see if you can change line "default calendar" to yahoo.

Go to settings and mail contact calendars

Add yahoo account and make sure calendars are on after you do. See if that helps.

What you trying to do has nothing to do with apple techs. You are trying to sync yahoo calendars. There use to be option in itunes to do that, but not anymore since Apple moved on to another more reliable platform - icloud. Your sync can only happen one way - if yahoo supports it. The way to do that is precisely what I told you - you have to have yahoo mail account and make sure yahoo is your default calendar. If that does not work, no apple tech will help you, cause it will mean that yahoo does not support it. You can a) stay with yahoo calendars b)move on to something that works like icloud, or Google exchange - paid service from last January.

BTW it is quite possible that yahoo's paid service will support that feature, but to find that out you may have to contact yahoo support. You may find out that their support is more expensive then apple's.