copy node set-up

How do I copy a node set-up from one file to another? I’ve tried selecting the nodes and making a group out of them but Blender is telling me it is not a group.

Selecting nodes and Ctrl+G to make a group. Save blend. Open new blend and append node group from first blend file. In node window with the correct node tree type selected (material / texture / composite) Add / Group / the appended node group.
Just tried with cycle material nodes and composite nodes and works as expected

thanks Richard, that did it for me.