Calling outside function

Question

This might be really remedial, but I am trying to run a function upon a button being clicked. I want that function to call a seperate function outside of the Click function. It tells me it needs an argument but not sure what argument to give. Any ideas?
mNav.about_btn.addEventListener(MouseEvent.CLICK, aboutGo);
    function aboutGo(event:MouseEvent): void {
        enterSite();
function enterSite(event:MouseEvent): void {
    var alphaTween:Tween = new Tween(mNav, "alpha", Strong.easeOut, 1, 0, 3, true);
    var yTween:Tween = new Tween(mNav, "y", Strong.easeOut, 250, 460, 1.5, true);
        alphaTween.addEventListener(TweenEvent.MOTION_FINISH, removeMnav);
            function removeMnav(event:TweenEvent):void {
                removeChild(mNav);

Answer 1

Try the following it should work
mNav.about_btn.addEventListener(MouseEvent.CLICK, aboutGo);
function aboutGo(event:MouseEvent): void
enterSite();
function enterSite(event:MouseEvent = null): void
    var alphaTween:Tween = new Tween(mNav, "alpha", Strong.easeOut, 1, 0, 3, true);
    var yTween:Tween = new Tween(mNav, "y", Strong.easeOut, 250, 460, 1.5, true);
    alphaTween.addEventListener(TweenEvent.MOTION_FINISH, removeMnav);
function removeMnav(event:TweenEvent):void
        removeChild(mNav);