Transferring files manually

I have a mid-2010 Mac Mini. I reinstalled lion on it because I am using it solely as a server now. Before I wiped it, I manually moved my desktop, minecraft server, documents folder, and music folders onto an external hard disk. After I restarted, they all say "The folder 'X' can't be opened because you don't have permission to access its contents"

I really want to be able to get at my old stuff. Please help