[MX04] [Help]Spaceship Game Coding

[~ZOMG~]

Hi, i'm making one of those spaceship shooter games.
but i have a few problems,

1. at the end of the level, you fight this boss, but when you defeat the boss how can you make it that it'll go to the next scene/frame (or something)
i tried to attempt it with: (if you really wanted to know)

if (boss=dead) gotoAndPlay("2", 1);

2. You start off in the game with 10 lives. But when you have 0 lives, how do u make the game say game over or something?

any help would be appreciated thanks.