Did you already install RailsGame?
After that, just edit private_variables.sh (see below) and then type "./run_server.sh". Eventually you'll want a larger, more robust deployment, but in the beginning you should just run everything on a single server.
Having trouble? The TROUBLESHOOTING file may help.
In your new RailsGame project that you created from the template, find the file called "private_variables.sh". You'll need to tell it the address your game will be running at (maybe "localhost"?) and the port number to run at (pick something distinctive). You'll also need to name your game. Don't worry, you can go back and change it later, so you could just leave the sample name.
Once you get to the optional and advanced stuff later in the file, you can probably stop, especially if your eyes have already glazed over.
If you said you wanted email activation, you'll need to give valid info for your mail server. That's probably information from your ISP, a lot like when you set up your email client. If you do that, your game will send email from your address at your ISP when people sign up for new accounts. That's probably what you want it to do.
You'll also need to give an email address for yourself that's valid. A lot of places won't accept an invalid "from" address, to prevent spamming. So for the admin email address, use a real one.