Hi,
Are you able to access other rubygems executable? e.g. rake, rails etc
It looks like your PATH variable does not have directory where 'webroar' executable have been installed.
Execute 'gem env', you would get few key-value pair in output. In that you can find EXECUTABLE DIRECTORY. Please check 'webroar' executable in EXECUTABLE DIRECTORY.
Please let us know, if above doesn't work.
Thanks,
Dharmarth