how should i make a directory

hello all
I am having a chat application in which I have to use LDAP as the driectory service .I just wanted to have the nicknames of the user in the directory.

So how should i be making the directory when i am having openLDAP as the directory server for Windows platform

How should i proceed to create this type of directory

And what should be the exact procedure if i just want to add the names to the directory while users authenticate and remove the names when thry are offline

Or should i have their names intact only i should change the flags when they are out of chat

Thanks
Regards
Monarch