I have installed rubyand am now trying to install rails, but keep getting an error.

from the command line C :\ruby\bin>

ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
getaddrinfo: no address associated with hostname. <SocketError>
Can anyone help me resolve this.

Also, I have xampp installed as my local testing server. Can I use the mysql already installed with RoR? I am a little confused as to how all this works.