Creating an email account as a way to share files is lame and inefficient.
Sharing files is pretty easy. I'm assuming you've got Windows XP. I haven't ever used or needed to use the wizard rrcn mentioned, but that may be a great place to start. If you have XP HOME, the default workgroup is "MSHOME" if you have XP Pro, the default workgroup is "WORKGROUP"
To find out your exact workgroup name, as its enterily possible you may not be using the default names, simply right click on "my computer" and go to "properties" then the "Computer Name" tab. This tab shows you not only the workgroup name, but the name of that individual computer. If you want to name the PC or even the workgroup something else, this would be the time to do it. You will want to do the same step on the other PC, making sure the workgroup is the same but that the computer name is different.
After that its simply a matter of right clicking on the drive or folder you wish to share and click on the "sharing and security" option. Once you get there it should be pretty self explanitory.
You can then go to the other computer and brows the network through "my network places" find the PC with the shared resources and viola, you're there. Once you find it you can also map a drive letter to it so that you can access it from "my computer" just as easily as you would your local hard drive. Simply right click on the shared resource and click on the option that says "map network drive"