How to start a project with CodeIgniter?

[eluser]Mauricio de Abreu Antunes[/eluser]
Hi,

I'm new to CI and trying to build an intranet for an english school.
Currently, i'm using 2.1 CI version.
I dont know how to start my project even working with PHP for 2 years.
I know what is MVC because i work with Java/ASP.net, but the question is: how to integrate correctly CI with any project? Is there any "best configuration" for CI?
How to use routes without errors?
How to use friendly urls without errors?
Use or not use Smarty?
What about security using CI?
When do i use slug and how to use them?
Please, redirect me for the right post in this forum.

Thanks and regards.