Head Oil Leak? How do i fix this? 2001 Honda Civic LX?

i had previous posts of a oil leak on my valve cover, and i found the leak. it's not with the gasket but to the left side of the engine by this plastic ';cover'; looking thing right by the calve cover. its a round plastic cap thing. how do i fix this? can i pop it off and use RTV Silicone? or can i buy this part?





thanks in advanced.Head Oil Leak? How do i fix this? 2001 Honda Civic LX?
Round plastic cap thing? Its not the cap where you pour the oil in is it? If so then just get a new cap.