How do you know when a guy likes you?

my brothers friend who is 2 years older then me added me on facebook i never met him before but i looked at his piccs and he was really hot so i wanted to talk to him so i inboxed him and said do ik you and hes like idk, i heard u were ______'s sister so i answerd and said oh yea i amm...i then saw him in school a few times and stuff and then a few days later he inboxes me again and say....your hot btw=]...but a few mins later says lolollol sorry that was my friend......do you think he likes me im not sure i think hes realllyy hot and i wanna get to know him better but we didnt continue the convo...:(