How do I configure Tor, once I install it, to work. An error message says it's missing one of two files that Vidalia needs to start up. I'll give you the exact message when I try to install it again if you want it.
You can configure Tor by editing your torrc file.
Tor manual explains different available configuration options in detail.
Please note that editing torrc file is intended for advanced users and Vidalia interface can be used for basic configuration (once you're able to run it, of course):
Tor installs a text file called torrc that contains configuration instructions for how your Tor program should behave. The default configuration should work fine for most Tor users. Users of Vidalia can make common changes through the Vidalia interface — only advanced users should need to modify their torrc file directly.