very easy. turn your steering wheel all the way to the side. behind the wheel, look for the part in the picture. cut a tiny slice with an exacto knife where i've highlighted in red. put the WD40 spray tube into the slice & give it a good squirt. go for a drive so the WD40 gets evenly distributed & cleans out the nylon.
turn your steering wheel all the way right. look behind the left wheel down low. you will see a control arm that connects the wheel to the car. the ball joint will be at the outermost point of this control arm.