[take off the radiator cap and look]
Update: Actually, there is no radiator cap and therefore no way to check the level directly as the questioner wants to do. When refilling the radiator, you have to go through a bothersome process of filling up the reservoir, then "burping" the air out of the radiator by squeezing the upper radiator hose (the large hose on the right side.) Then you add some more coolant, burp some more, etc until you can't squeeze any more bubbles out. Then you have to run the engine until it is warm and water is circulating, then turn it off, let it cool, and repeat the whole burping process again.
All designed to prevent lawsuits from idiots who burn themselves by opening the cap while hot.