The yellow one is the engine oil, and should have a clover imprinted into it.
If its below min, get some more oil in it ASAP! Make sure you check it when the engine is cold and hasnt been run though, as when the engine has been run the oil sits in the heads etc until it drains down to the sump (dip stick measures sump level).
The black one i dont have on my car (v6 manual), so i assume its for the auto box, in which case it shouldnt be black (oil should be red. black indicates its burnt usually), and the oil should be checked with the car running, in gear.