Determine the type of carpet pad that you would like to purchase. For example, there are carpet pads made especially for oriental rugs, pads made out of organic materials or even pads that consist of recycled rubber. A non-slip, non-skid rug pad that is about 1/4 inch thick can work for most area rugs.
Measure your area rug with a measuring tape to determine the size of the carpet pad that you will need.
Purchase the carpet pad; rug pads are available at most places that sell carpeting.
Trim the carpet pad if needed; the carpet pad should be about 1/3 inch smaller than the area rug.
Remove the liners on the pad and place the pad on top of the floor or wall-to-wall carpeting. Cover the rug pad with your area rug and smooth it out so that there are no wrinkles or bumps.