Dorothy, pet stores have products that are made to remove urine odors. These will work if you just have an odor problem. If you have white marks in the area, the problem is limited to the floor's finish. The "worst case" is that you have to refinish the floor but there may be some things to try first. If you have black marks, this indicates that the wood is stained and permanently damaged. Again, the severity will determine whether you can sand the whole floor to remove the problem. If this is really severe, you may have to "borrow" some flooring from some place like the back of a closet or try to find matching new flooring to replace the stained wood.
If you can give us more specific details on the nature of the problem, we can try to give you more direction.