Most infants will spend their energy trying to get a ring on the spindle.  This takes an enormous amount of hand-eye coordination and determination.  It is not at all important that infants put the rings in order, as that would be developmentally outside of their wheelhouse, but you can model putting them in order for them.  They love to pull them off and throw them around and then you can put them back on the spindle so they can pull them off again. This repetition will reinforce the idea of the sequence, not only in the order of the rings, but in the order of the play.