2 options here:

1. You can save the figure to your browser by dragging the collapsed figure name from your properties tray to the Carrara browser in the Objects>My Objects section. This way you'll be able to drag and drop the figure into any Carrara scene you're working on.
2. Just save the file. You can then import the .CAR file into any new scene.

Both methods actually save the file in Carrara's format; dragging the figure into your browser makes life a little easier :)
You may need to make sure that your Poser Runtimes are attached to Carrara's content browser; just to avoid any missing files if your figure is using texture maps from other vendors; that kinda thing.