Do you mean inside the car?
If you mean under neath the passenger side of the car it could be the driveshaft CV joint rubber has a hole in it the lubricant in here is usually green. This is quite an easy job to do, but it does (I think) envolve stripping the drive shaft from the front wheel to slide the rubber off and on. There may be a full description up in another section. The procedure will be very similar.
If you have a workshop manual it will certainly have that job in it.