Without a model number I do not know what type of Roper refrigerator that you have. On most Roper brand refrigerators that have a water filter, the filter is located on the left side of the bottom front grill (Key 11 in the image below).
To remove this type of filter, carefully turn the filter counterclockwise until it stops. It may be hard to turn if it has never been removed for the first time. After turning it to the left, pull it out of the housing. Remove the decorative cap and place it on the replacement filter. Push the new filter in and turn it to the right (clockwise). Purge air from the dispenser system by running the water dispenser as constantly as possible to remove about 3 gallons of water (if the refrigerator has a water dispenser). This will keep the water dispenser from dripping.
If you have a different type of Roper refrigerator, resubmit your question with the full model number off of the unit.