Q: iCloud Keychain Basics

I want my existing OS 10.11.6 iMac iCloud Keychain passwords to be available on my iPad and iPhone.

First I added a 6 digit security code to iMac iCloud Keychain.  Then I did the same to my two devices, that is, I added the identical 6 digit security code.

When I used a device to go to known websites, I expected that I would be prompted to sign in with my existing user name and password.  No luck.

Either my concept of the use of iCloud Keychain is wrong or I have not completed the steps properly.

Any thoughts?