My websites been hacked, Help :D

Hi everyone, i have a problem with my websites advertising and im guessing someone here will know what it is.
My site is FilmHammer.com
First of all m concern is that i think my site has been hacked because an advertising box at the top right corner of all my webpages has appeared, as well as links throughout my articles and text have popped up. Im definitely sure i didn’t add this to my site and i know my free hosting doesn’t place adds on their as well. Im new to web creation and i may have overlooked security of my site or something. Is there any way i can remove these and stop it happening again. Also is there anyway i can find out who has done it too.
Thanks for your time and hopefully your replies

See original post by MafiaPenguin