Once your keychain has been upgraded to the Agile keychain format, it is time to move the keychain file to your Dropbox. Before moving your keychain, I recommend creating a 1Password folder within your Dropbox. This will make the file easier to locate in the future as files accumulate with your Dropbox directory.
To move the keychain file, launch 1Password and go to the Keychain tab in the Preferences menu. Under location, click "Move" and a dialog will appear asking for a new location for the keychain file. Select the 1Password folder created earlier in your Dropbox directory and click "Change Location"
Quit 1Password and make sure your Mac is connected to the Internet. Wait for your keychain file to be uploaded to the Dropbox servers and the process is complete. From this point on, any changes made to the 1Password keychain on any of the synchornized Macs will be uploaded to the Dropbox servers and copied to the other Macs.
An added benefit of storing your keychain with Dropbox is that in addition to having your data synchronized, it is also backed up safely on the Dropbox servers. For more information about moving your keychain to your Dropbox, visit the guide provided here by 1Password.