How can i tell if my Chanel bag is fake or not?

Question

Mine looks like this and was given by a relative:

http://broccolicity.files.wordpress.com/2008/03/chanel-grand-shopping-tote-in-white.jpg

(With black Cs instead of white).

It had tags and everything that said it was authentic and it's made in Paris, France. The inside is like soft leather but i can't tell if it's real or not?

Help?