fetchmail and procmail for iRedMail 0.8.3 how to

Hi. I want to use iRedMail for an office mail server. But i want download mail from one mailaddress ISP and selectabe for users but how i can get this? I read befor topic but i dont understan. Sorry my wrong englis.
I find this: http://www.iredmail.org/forum/topic480- … tting.html

If i use LDAP only change ldap setting but how?

I need a step-by-step tutorial for use fetchmail procmail or other solution in iredmail virtualuser.

==== Required information ====
- iRedMail version: 0.8.3
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  LDAP
- Linux/BSD distribution name and version:  UBUNTU SERVER 12.04
====