[Rails] Error in ROR App on running code

hi all ,
I am getting error when i try to run my app. from Radrails, also when
installing "gem install ruby-gd" it shows some error,
Can anyone provide the right installation steps and libraries name which
required to install gd libraries ?
thanks in advanced ......



D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`gem_original_require': no such file to load -- GD (LoadError)
from D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`require'
from D:/Documents and Settings/Administrator/My Documents/Aptana
RadRails Workspace/suggestica/config/../lib/captcha_image.rb:22
from D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`gem_original_require'
from D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`require'
from D:/Documents and Settings/Administrator/My Documents/Aptana
RadRails Workspace/suggestica/config/environment.rb:24
from D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`gem_original_require'
from D:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in
`require'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/rails.rb:147:in
`rails'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:113:in
`cloaker_'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/configurator.rb:149:in
`call'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/configurator.rb:149:in
`listener'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:99:in
`cloaker_'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/configurator.rb:50:in
`call'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/configurator.rb:50:in
`initialize'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:84:in
`new'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:84:in
`run'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/command.rb:212:in
`run'
from
D:/Ruby187/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:281
from D:\Ruby187\bin\mongrel_rails:19:in `load'
from D:\Ruby187\bin\mongrel_rails:19
from -e:2:in `load'
from -e:2

Thanks and Regards
Sachin S. Kewale