Silicone can be applied to your cube in a few different ways, you can just pop a piece out, spray some in and turn it a little to get it worked in, and take the entire cube apart, spray each piece on each side individually and put it back together, this is the best method as it gives a smooth and equal turn on each side of your Rubik's cube, so one side won't be super smooth, and the other sides not so super.
