External hard drive. Permission denied???

I just bought a used 400gb hard drive from a friend. i put the hard drive in a external case. The hard drive only gets recognized in the disk utilitty. When i try to foramt it. I get a error message that says permission denied.

Is the hard drive locked?
Is there any way of unlocking it?
What can i do to make format and work?

Thanks to all who help

If you right click on the HD, get info, are the permissions read and write for system and admin, and is it formatted in HFS+ (Mac os extended journaled)?