problem to update ruby

[Maite Piedra]

hi list
I have to try to update ruby version I have a mac
I have install this in my computer
ruby 1.8.6 (2009-06-08 patchlevel 369) [universal-darwin9.0]
gem -v
1.0.1
Rails 1.2.6

i try with this
sudo gem update -- system
Password:
Updating installed gems...
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 302 fetching http://gems.rubyforge.org/yaml

with this
gem install rails -v=2.3.2 --source=http://gems.rubyonrails.org
Updating metadata for 73 gems from http://gems.rubyonrails.org
.........................................................................
complete
ERROR: Error installing rails:
rails requires rake (>= 0.8.3)

and this...

sudo gem install rubygems-updatePassword:
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 302 fetching http://gems.rubyforge.org/yaml

or this

$ sudo gem install rubygems-update --source
http://gems.rubyforge.org/yaml
Password:
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 302 fetching http://gems.rubyforge.org/yaml

someone can help me to update rails. :/

Thanks