I just want to find out the version number of subversion we are running on our windows server, but I don't know how or where to input the $ svn --version. ANy idea where I type it in?
svn --version will tell you the version of the svn client .exe, not any particular server.
You need to find the svnserve.exe which is running on your server, and run that with svnserve.exe.
But see also: