Hide and unhide my gun mouse

Hello all. I am making a first person shooting game for my school project for my final. All is working well at this time, but I want to add another scene and I am not sure how to do this. Im using Flash MX. The code I have so far is:

var i;
// gunfire sounds
var gunfire = new Sound();
gunfire.attachSound(“gunfire”);
_root.hit1.onPress = function() {
gunfire.start();
i++;
// make bullet holes
_root.bull.duplicateMovieClip(“bulletNew”, i);
if (i == 10) {
i = 0;
}
// hit test on target
if (_root.target_mc.hitTest(_root._xmouse, _root._ymouse, false)) {
// play explosion
_root.gun.gotoAndPlay(2);
// send target off stage
_root.target_mc._x = 0;
_root.target_mc._y = random(400);
}
};
// initialise stuff
_root.onLoad = function() {
// hide the mouse
Mouse.hide();
};
//loop
_root.onEnterFrame = function() {
//put cross hairs to mouse coords
_root.gun._x = _root._xmouse;
_root.gun._y = _root._ymouse;
// target move
_root.target_mc._x += 10;
// if it goes offstage, send it stage left
if (_root.target_mc._x<0 || _root.target_mc._x>Stage.width) {
_root.target_mc._x = 0;
_root.target_mc._y = random(400);
}
};

I am looking at a button to add to send my movie to scene 2. What would the code be to show my mouse over the button I wish to use and where in the code line would I insert it?
Thank you all in advance