Website looks weird with mozzila

i think i probably posted this in the wrong section so i just pot it in both. Delete or move the wrong one plz.
Ok i uploaded my stuff into freewebs and whatever… and it looks fine with internet explorer… but then when you use firefox to view it then thats where oyu see the problems website. Plz help.:*( edit o btw i used microsoft front page to edit it a little.