Ruby on Rails, can't tell if I've installed properly

I've just installed Ruby on Rails, and am ready to start running through tutorials, but when I type

heather@heather-laptop:~/RubyProjects$ rails demo

I get

Usage:
  rails new APP_PATH [options]

Options:
  -G, [--skip-git]            # Skip Git ignores and keeps
      [--dev]                 # Setup the application with Gemfile pointing to your Rails 
checkout
  -b, [--builder=BUILDER]     # Path to an application builder (can be a filesystem path or URL)
      [--edge]                # Setup the application with Gemfile pointing to Rails repository
  -m, [--template=TEMPLATE]   # Path to an application template (can be a filesystem path or URL)
      [--skip-gemfile]        # Don't create a Gemfile
  -d, [--database=DATABASE]   # Preconfigure for selected databas开发者_StackOverflow中文版e (options: mysql/oracle/postgresql/sqlite3/frontbase/ibm_db)
                              # Default: sqlite3
  -O, [--skip-active-record]  # Skip Active Record files
  -r, [--ruby=PATH]           # Path to the Ruby binary of your choice
                              # Default: /usr/bin/ruby1.8
  -J, [--skip-prototype]      # Skip Prototype files
  -T, [--skip-test-unit]      # Skip Test::Unit files

Runtime options:
  -f, [--force]    # Overwrite files that already exist
  -s, [--skip]     # Skip files that already exist
  -p, [--pretend]  # Run but do not make any changes
  -q, [--quiet]    # Supress status output

Rails options:
  -v, [--version]  # Show Rails version number and quit
  -h, [--help]     # Show this help message and quit

Description:
    The 'rails new' command creates a new Rails application with a default
    directory structure and configuration at the path you specify.

Example:
    rails new ~/Code/Ruby/weblog

    This generates a skeletal Rails installation in ~/Code/Ruby/weblog.
    See the README in the newly created application to get going.

Am I doing this properly? Do I need to add a flag?

You need to use new... exactly what the output says...

rails new [Application Name]

Usage:
  rails new APP_PATH [options]

As the above output says, you missed the new.

To get started on Ruby on Rails, go through these guides Getting started with Rails 3