Next, spray the affected area with an enzyme based digestive cleaner such as Spartan's CX3 Bio-Assist (make sure the cleaning product is approved for your carpet - follow manufacturer instructions). Lightly scrub the area then blot dry with a paper towel. The cleaning solution contains natural enzymes that will remain behind and a few hours after application will "wake-up" and start to "eat" any remaining odors.
If the urine soaked into the pad below then you will want to rent a carpet extractor. You can follow the same steps above but the extractor will also help to remove urine from the pad as well get the odor eating enzymes in there to continue to combat odor.