The set comes with 3 actions:
Snow, More Snow and Add Tone (5 winter tone options).

How The Snow Action Work?
After installing the action run EITHER Snow OR More Snow action.
Note: you must run the action on your Background layer.
Let the action finish before you move on.
It might take a while for the action to be done running.
After this you can run the Add Tone action.
This action will create 4 tone options for you to toggle on/off.
What comes to the snow layers, you can move them, duplicate them and if you feel there is too much snow you can turn off any layer.

This action has been tested and working on:
Photoshop CS2, CS3, CS4, CS5, CS6 and all Photoshop CC.