Hi ussfolsom,
This summer I built my first network and it's not that difficult. There is an Apple extension called printer share that will allow you to share the 2400 over a network without any kind of adapter, as long as the computer that the printer is connected to is running and Appletalk is on.
I stongly suggest that you buy a hub. Small ones (especially if limited to 10BT speed) are cheap and then your network is easier to manage and expandible with ease. I built my own cables ( a bit of a learning curve here, but cheap and just the correct length ) and it works well with 3 Macs and one networkable printer and 2 old stylwriters via printer share.
Use the Mac OS setup assistant for the easiest way to be sure that both computers have a name and password for the network. Open the appletalk control panel, select "ethernet" as the port, and be sure that it's turned on. Depending on system software, there are several control panels and extensions that are necessary for it all to work, but they are usually installed by default so just be sure that you have them enabled. (Appletalk, file sharing, network, various extensions and libraries)
Apple's network browser is a good way to see if it's all working when you're done. Then you can set up your printer via the chooser.
Have fun.