oil leaking into spark plug

hi there is oil leaking into the first spark plug causing the engine to steam and overheat in my ford ka 1.3 (endura e ) the oil is coming from the place highlighted in red in the attached image. i would like to know what part it is and what you think the problem is , also the path in which the oil goes to seep into the spark plug is shown in the picture , please answer asap , thanks