Create new project:
rails new Project_name

Generate Scaffolding:
rails generate scaffold col1:type col2: type col3:type col4:type

DB Migration
rake db:migrate

Run project
rails server

Watch route info in browser:
http://localhost:3000/rails/info/routes

Install new Gem:
bundle install
bundle add

if we manually add a Gem in Gems file, then we have to give following command :
bundle install