How do you report harassment in youtube?

so i commented on a video that i like saying that i admire the person on the video. and someone with username EmJeY015 replied on my comment calling me moron. etc. so i was shocked and insulted and replied him back saying he's such a disrespectful kid. and then he replied back saying more mean things and so on. i replied back again saying he's really really mean, etc. and then when he replied back, he turned the table around and claimed that i was stalking him and he even ask for help from other people pretending like he's the victim! WTF. how do i report him? i can't find any link in youtube about reporting harassment.