Somone please tell me what this is
 

OK i tryed looking on alldata and didnt find anything and people om my outher form cant tell what it is its leaking the whole thing not just the oil filler THE WHOLE THING i know what i highlighted in blue is the valve cover but what is the name of what i highlighted in yellow i need to replace the gasket thanks: http://i179.photobucket.com/albums/w293/CLK_011/Wherewerace001-2.jpg

That is the upper portion of the valve cover....sealant is used to seal it to the valve cover.