Recording a song with a mic that comes with your headphones?

I'm just wondering.. I know how to make my vocals sound like a studio quality on cool edit pro but every time I record, even when I say nothing, I always turn my fan off and still hear the backround noise.. I got enough money for some egg crate foam to spread around my room when I go to newcastle for the holidays.. So can someone tell me why do U hear the backround noise everytime U record with a mic on headphones even when it's totally quite.. I hope that backround noise will stop when I record when I spread the egg crate foam around my room..