Codeigniter vendor folder use

i have installed codeigniter using composer ( $ composer require "rogeriopradoj/codeigniter 2.2.1-rc.2" ) There i got folder structure on root
-application
-vendor
and system file was in vendor folder. I m quite confused whats the use of this vendor folder. And how to start project . Please help me out.

The vendor/ directory is a Composer thing. If you've used composer before, you'll know what to do with it, but for CI in particular, you just need to specify in index.php the location of the system/ dir.

But anyway, that's not why I'm replying ... the only official CI repository for composer is codeigniter/framework. What you've used is made by a random user and is outdated and insecure.