Two sites - one ci

[eluser]dianikol85[/eluser]
As the title says I need to run two sites with one installation of CI 2.0.

The first one is the backend and the second one the frontend. A CMS like. What i need to do in order to achieve that?

I am sure that i need to have to application folders but i don't where should put them and what other configuration i need to do.

For example:

1) website.com : the front-end, the actual site for users

2) website.com/administrator : the back-end where i make changes like inserting data to a db which data are going to be shown in the front-end.

I'm sure many people here need to do this.

Thanks in advance!!