beginner question on ruby sql

[nkb]

Hi.
When I run sqlsh.rb from my c:/ruby, I received the error

c:/ruby/lib/ruby/1.8/irb/completion.rb:10:in 'require': no such file to
load -- readline (LoadError)
from c:/ruby/lib/ruby/1.8/irb/completion.rb:10
from c:/ruby/bin/sqlsh.rb:42:in 'require'
from c:/ruby/bin/sqlsh.rb:42

What am I missing here? My ruby is installed from file
rubywin181-13.exe. Thank you.