Hi,

what you must have first and for all is a crossed cable. This is a network cableto connect to computers without hub or so.
This cable typically has red plugs.

Anyway, after you plugged in your computers, you need to set the ip addresses for both computers. How to do that, and which ip addresses you can use, you'll have to see on the net, otherwise I'll tell you later.

now look up the destined IP address, and log on with your credentials... Now you can transfer files.

If you activate ftp on the mac, you can up and download files as on the internet...