Please, HELP!

I'm playing journey to Pompeii, after the donkey runs around town with the sign this guy asks me to come with him to the Grand Palestra. I come with him and he says to throw the spear, so i do. If u aim @ sum one he dies, but besides that i don't know what to do! is there somewhere in particular that i have to throw the spear if so i've thrown it everywhere and all i can do is throw it again! Is there somethin' i have to find or somewhere i have to go? i have no clue, please help if you can.
FM89