Tree Control select method called itself

[MFCQuery]

Ok Let me explain this in detail.
I have one MFC dialog base application. On the dialog i have tree control and list control. Lets take example of window explorer. In left pane we have directories and in right pane we display subdirectories and files of this directory. All these data i'm storing in a dll (directories/subdirectories). So when i click on any directory in left pane i call a function of dll where i pass this directory name. Dll searches all subdirectories and files and insert in right pane.
From dll i can insert item in tree/list control in some variable which i pass from exe. But i dont know how to call refresh method of list/tree control from dll to make items visible. I have tried to implement dll in regular dll or ATL com dll.
Now suppose i dont have exe code but i have exe. I have dll code. Now from this dll code i have to insert items and refresh them.

Let me explain the problem now.
Suppose i click on any directory in left pane, exe call one function of dll which search all subdirectories and files and insert them in variable which i pass from dll. So i can see all sub directories in right pane. Now Suppose if user right click mouse on any item in left pane a popup menu is display which contains "Show". If i click on show then i want same functionalities like NM_CLICK. For this i call same dll function which insert all subdirectories and files in right pane. But it doesn't display them. So here i think i need to refresh right pane from dll. But i dont have idea how to do this.