Where do you add power steering fluid in an infinity j30?

[B sack]

I can not figure out where to add the power steering fluid i would greatly appreciate it if some one could help... I looked at every thing i can add it to, but all i see is an unlabeled one, break fluid, coolant, and wiper fluid. i believe it is one that is to the left that has a large black cap on it, but i am unsure...

 

[greasejunkey]

yo, dipstick, its next to the oil dipstick, its that bulky looking black box with the screw down lid on it.