If i'm blog about a celebrity am i allowed to use a photo of them that i found online? lets say when britney spears shaved her head and the photos of her where all over the internet with shaved head. Am i allowed to use those photos in my blog.
All pictures have an automatic copyright. You need permission from the copyright holder (often the photographer) to legally use the image. There are instances where "fair use" can be applicable, but unless you are a school, legitimate news source, etc., it won't apply. I'm assuming that your site is a "commercial site" (takes in any type of revenue - advertising, adsense, donations, etc.). There are a lot of sites that are guilty of copyright infringement - most don't get caught, but those that do can wind up paying thousands of dollars per image.
I've heard that, in some cases, celebs have extra protection of their images (and names and voices) not available to photos of ordinary folks.