For GMC (C/3C and C/4C), feed the rank through each epaulet, making sure the bigger end of the rank is at the shoulder end. Make sure the lines of the soft rank are pointing outward from you rather than pointing inward on each shoulder. Imagine the bars are like your feet when you are standing at attention.
For POC (C/2d Lt - C/Col), feed the rank through each epaulet, making sure the bars of your rank are at the shoulder end.