[Fmx - 6] Fire Tutorial Help!

Hello, I am having a little trouble…Ok you know the fire tutorial right? well see I want to use that to make a little game where its 2 players and You have 2 crabs (or characters) that shoot at eachother like 1 on the top facing down and one character faceing up and you try and shoot eachother but see I need help making a boundries for the characters and also I want it to where when bulet hits Other character then the character will Explode or GotoFrame (whatever like Lose or Win) Im sorry I kind of explained this in a complicated way but if you could help id appreciate it - thanks - Jereth Miller