Address Book on iMac is out of synch with Contacts on iPod Touch. How do I get them in synch (through iCloud/iTunes)?

I'm confused about the different versions of Address Book on iMac. I set up iTunes to synch Address Book with my iPod Touch 5th Gen. through iCloud. Somehow they got out of synch.

There are three sections or versions of Address Book on my iMac: (1) "All Contacts," (2) "On My Mac: All on My Mac" and (3) "iCloud: All iCloud."

"All Contacts" seems to combine the last two. Unfortunately, contacts that got added to "On My Mac" are NOT being synched to iCloud and to my iPod.

What can I do to get them in synch and how can I avoid this in the future?