Have been using this function and find it very useful for organising things.

Pretty much as ThrommArcadia says, except you don't even have to go to top of menu to add to collection...

Just highlight the figure, prop, whatever you want to add to your collection and do a right mouse click...

It is nice in that you can add anything to a collection... figures... hair... props... poses.. etc.

Have started to make a few collections and it will certainly save some time later when composing scenes. Instead of sifting through various folders... even runtimes... for things... you have them all in one place.

"You don't have to be mad to use Poser... but it helps"