The one close to the arm rest or up by the radio?
Either way here's what you do:
One by the arm rest: Flip the lid if its there, pull up on the black part from inside the cup area. Replace with new one.
One by the radio: Remove the arm rest area cup holder as detailed above. Then, there are two screws behind that--remove those. Next, pull your parking brake. Using the shift lock button, pull the shifter to D and then slide down the bottom cover to expose those two screws. Remove those two screws and pull the shifter off.
Next, pull up on the shifter trim piece and unplug the connectors. Then, remove the screws that hold the center console trim in place. When that's finished, remove that trim and flip it over. Take out the plugs for the hazards, temp, and volume controls. Then where that cup holder or the pocket is depending on your year of SC, push the little pins out gently and replace it with the new cup holder.
Installation is reverse of the removal.