New to rails. Just trying to understand these two files in the \\assests directory.
For example, the application.js file has lines such as:
//= require j
It's rails magic! So no you cannot see the files within your own project directory. If you are really curious you can checkout the code for the gem on the gem's github page https://github.com/twbs/bootstrap
Also, if you really want to change something in the gem, you can fork the code into you own github, change things on your local branch, and then specify your own github as the source for the gem in your gemfile such as...
gem 'twitter-bootstrap', :git => 'git@github.com:my_github/twitter_bootstrap.git'
But, you might not want to try that if you are really new to rails ;)