icloud on mac mini ,ipad mini and iphone?

Sure, go to Settings>iCloud on your iOS devices and sign in with your Apple ID to create the account, then turn on the data you want to share with iCloud. Then go to System Preferences>iCloud on your Mac and sign in the the same ID and check the data you want to share using iCloud. See http://www.apple.com/icloud/setup/.

On your iPhone the settings will look like this:

It might look similar on your iPad but I don't have one to show.

On you Mac Mini it's this:

If you want to have Photo Stream setup in iPhoto on your Mini setup iPhoto's Photo Stream preferences like this:

OT