First step with Joomla

Hi !!
I'm ready to opena site where i can sell videos and mp3 created by myself, i have dw Hika and i see it in the components of Joomla; i hav cretaed some categories and products, but everytime i don't see these categories in the site, instead i see just the modules create just with Joomla.
I have created others categoreis and for each categories a lot of porduct, but i see nothing in the site....
I have not uderstand, where am i wrong?