Actionscript 3 code explanation to understand the logic?

Hi,

Please help me to understand the following code (the logic in using it) line by line:

 
navContainer.y=stage.stageHeight-60;
navContainer.scaleX=stage.stageWidth/980;

header.scaleX=stage.stageWidth/980;
 
mainContainer.x=stage.stageWidth/2-mainContainer.width/2;
mainContainer.y=stage.stageHeight/2-mainContainer.height/2;
 
mainContainer.welcome_image.x = stage.stageWidth - (stage.stageWidth/980)*540;
mainContainer.welcome_content.scaleX=stage.stageWidth/1020;

Thanks.