Can't Access a file I downloaded since I don't have permissions yet I am admin?

"Check file/containing folder permissions and ownership. There should be something wrong with them. This message is typical if you tried to play with them before and messed settings up. If you are the owner than you can override security settings to allow you do whatever, otherwise you'll have to force-override the owner first.

Check out this article. It has some pretty images and step-by-step tutorials."