create new application ruby on rails-Collection of common programming errors

I’m bit confused by “easy” working with ruby on rails, cause I already spend three days by trying create an app.

I work on site5 hosting, and try to create new app. step by step:

$ rails new app -d mysql

$ gem install mysql

$ gem install mysql2

and after

$ rake db:create

it report about error

Could not find gem 'mysql2 (~> 0.2.6, runtime)' in any of the gem sources listed in your Gemfile.

I google it, but still can’t fix problem. Can anybody help?