All you should need to do is turn on Personal File Sharing & Printer Sharing. These are two simple checkboxes in System Preferences -> Sharing -> pick the Services button and you'll see
this .
Then, switch over to the "Internet" button, Choose to "Share your connection from" "Built in Ethernet", check the "Built in Ethernet" check box, and hit "Start". You will get a warning dialog stating something to the effect of "Your ISP may disconnect you if you use internet sharing". You'll just have to try it to see if they allow it or not.
Screenshot
In summary: Personal File sharing "on" for BOTH machines. Internet sharing "on" for the computer with the internet connection. Printer sharing "on" for the computer that is connected to the printer. The whole process can be finished in 10 seconds if you know what you are trying to do.