It depends on which country you live in beleg_Strongbow.
I am not sure if you are referring to ratings (PG, R, etc). If so,ratings are usually set by a Board. My Aunt served on one of these boards for serveral years. As this was a number of years ago, qualifications have likely changed. I have pasted a link which may answer some of your questions: http://www.mpaa.org/movieratings/about/index.htm
As far as careers in the film industry. There are many colleges and universities out there offering programs. I am sure you will find one near you. I do suggest you consider university as the competition is very stiff in this field. I am afraid the market has been flooded with computer graphic specialists. That being said, creativty and talent go a long way. Try this link for more information on career choices in film industry. http://www.khake.com/page45.html
You can also try visiting some of the production company sites as they may have some career information or job listing that will give the qualifications they require.
I hope this is of some help to you.