[eluser]jkevinburton[/eluser]
First, Welcome to the CodeIgniter Forums.
I think I saw someone talking about creating a forums library, but dont know whatever happened to it.
CodeIgniter is a "BASE" - meaning, here's a simple platform, now go build your modules, classes, etc.
Meaning: YES - you will have to do your own coding. CodeIgniter is not a CMS, or a blogging system - if you need that, go with SMF or some other forum software.
Or you can purchase ExpressionEngine - which is a CMS with a Forum component - also from the same creators of CodeIgniter.
Web Application/Site Development is not a quick fix, do it right, build it yourself, OR hire a professional to do it for you.
Sorry for the harsh response, it just seems to be a common this around here.