How do I install this gem?

I'm trying to figure out how I can setup my own forums using Ruby, but I
can't get passed installing "nifty-generators"... I haven't a clue how
to install the gems... Please tell me what I'm doing wrong?

I open the command prompt, I type in :

gem install nifty-generators

And this is what I get:

Successfully installed nifty-generators-0.4.6
1 gem installed
Installing ri documentation for nifty-generators-0.4.6...
ERROR: While generating documentation for nifty-generators-0.4.6
... MESSAGE: Invalid argument - ./</cdesc-<.ri
... RDOC args: --ri --op
C:/Ruby193/lib/ruby/gems/1.9.1/doc/nifty-generators-0.4
.6/ri lib --title nifty-generators-0.4.6 Documentation --quiet

Pleassse help...

Paet Worlds II wrote in post #1043392:

gem install nifty-generators

And this is what I get:

Successfully installed nifty-generators-0.4.6
1 gem installed
Installing ri documentation for nifty-generators-0.4.6...
ERROR: While generating documentation for nifty-generators-0.4.6
... MESSAGE: Invalid argument - ./</cdesc-<.ri
... RDOC args: --ri --op
C:/Ruby193/lib/ruby/gems/1.9.1/doc/nifty-generators-0.4
.6/ri lib --title nifty-generators-0.4.6 Documentation --quiet

It's only failing to install the docs. Either add the option to gem
install to skip the docs, or do the actual right thing and put the gem
in your Gemfile and use bundler to install. That will automatically skip
installing the docs. The docs you probably won't use anyway.

An alternative for this strategy is to install a .gemrc in your homedir.

~$ cat ~/.gemrc