based on your other post about spell importing ..
well you have to do this all in trigger editor
if you know how to use it either in jass or GUI
You have to make a trigger with Unit Dies event , check who killed it and which team it belongs to , then rise the teams global variable which counts the kills
when a team reaches the kill limit the game ends.
easy task but you need to learn editing triggers
about the score board , little bit harder but the same, you need to know triggering