Bundle install

This is my solution. It may has a better solution than mine.

For Mac user like me, if you create the RoR project with NetBeans you need to copy the following files:

1. config.ru
2. Gemfile
3. Gemfile.lock

to your project folder. These file was created from Terminal(I use this one). Otherwise, you cannot type "bundle install". The program will show "Could not locate Gemfile", if you don't do above.