I want to separate Work and Home Calendar in my iPhone and iPad in iCloud. For example, just share the home calendar (no work calendar) in my iphone to my son and he will use my iPad. How can do setup in iCloud?

If your devices use the same Apple ID to connect to iCloud, then you'll get full syncing between all devices for those calendars that are defined in "iCloud" (as opposed to those defined "On my mac" or "On my iPHone). If you want to have someone else use a device and access some of your calendars, they should use their own account and then you can make whichever calendars you want "sharable" which you can do on icloud.com.