networking problems

I want to be able to see ALL files on my iMac from my G5 and vise versa. So far, all I can see is the dropbox and I cant see whats inside of IT. i want to be able to put files on my iMacs desktop from my G5. When i open the name of the G5 and try to open the desktop, it saus I dont have access privelidges. Someone help me here before I go crazy!

To see all the files on a Mac over a network, you must log in using your user account name and password. If you don't provide a username and password, you can only browse "public" files.