It's not clear what you mean by now you are blocked? Do you mean that you can't open your Lightroom catalog on your MacBook Air?
Well currently everything is on the desktop, nothing on airbook and iPhone. I would like to sync only some live previews from the desktop to the other systems but don't know where to start... many thanks in advance!
Okay - I think I understand... you had Lr running on a Windows computer. Updated to a MB Air. You want to share images in your Lr CC catalog from your MB Air across all devices. Does that sum it up?
Here is how you start.
Download Lightroom Mobile on your iPhone - it's free and available from the app store.
In your Lr CC catalog on your MB Air > sign-in to Lr Mobile under your name in the upper left most corner > Select any group of images and Create a Collection > in the left-most side of the column tap the sync icon to sync that collection. Lr will create smart previews of the images in the collection and sync them to Lr Mobile.
On your phone > open Lr mobile app > sign in. You will see the photos in your collection and you can continue to work on your images in Lr Mobile. Select a photo and make an obvious edit... change it to B&W. Then go to Lr CC on your MB Air and see the changes that you made once Lr finishing sync'ing.
The setup was almost righ, but the catalog thing did it thank you so much!
For correct setup I will simplify :
imagine only a desktop with lightroom cc
with 1000s of pictures
then buy an airbook and an iPhone and you want to work on your pictures on these systems too...
collections seem to work
Good to get you started anyway. Ideally you would share your Lr CC catalog on both desktop and laptop and use mobile for smart phone and tablet devices. Glad to hear that collections are helping you on your way.