Vista - access permission

I have my network finally able to see one another and can access public files. Some files I need to access I get a permission error, telling me I need to get permission from the administrator. I am the administrator so how do I give myself permission to do this. I did some Googleing but the only thing I can find is to right click file that I want to have permission and select properties. When I do It say I don't have permission to do this. How can I have full access to networked computer?