I have Lr 5.7 on my iMac and want to PS and LR creative cloud. Where do I begin and how do I make sure all my work in LR from iMac is in sync with CC??
The CC versions are just Upgrades from what you now have. When you install LR and open it for the first time it will find your LR 5 catalog file, Make a Copy of it and convert that copy to a LR CC/6 version. This will carry everything over to LR CC/6 without removing LR 5 or the LR 5 catalog file.
But first exactly what version of OS X are you using on your iMac. For the newest version of LR you need at least OS X 10.9.
I have 10.11.1 iMac. So, it should work. Thanks for the help.