How do I use the shoe stretchers from Aldo?

I bought a pair of pumps at Aldo for my best friend's wedding (I'm the maid of honor). I have a hard time with pumps since my feet are so narrow, and went down a size. The associates at Aldo gave me shoe stretchers that they said would stretch them one 1/2 size so that they'd be more comfortable. Unfortunately, I don't have the slightest clue as to how to properly use them. Has anyone else gotten these and know what they're doing?!