syncing problem between macs

It used to be that all my different Macs talked to each other and would update calendars, contacts, mail and such. It was wonderful. Now they don't.

I have always used my @mac.com even when they gave out the @me.com and then the iCloud.com. I have never changed my settings that I am aware of other than the use of iDrive and I am not even sure about that. It is turned on but I am not sure why or what it does.

Obviously I have missed a step along the way with all of the OSX changes. My desktop and laptop run on Yosemite and my iPad Air and iPod Touch are running the latest IOS.

Can anyone point me in the right direction to find how to fix this so that I have a happy Mac family again?

Thank you.