How to find out Active Process Book and Active Display from .Net VB Code?

Hi. I am trying to find out active Process Book from .NET VB code, but do not know how to initialize the object. For example, I want to find out the active process book to open some existing schematic or want to display some trend on the active process Book and active display. I am using the following code, but do not know how to initialize the object.

Dim objPB As PBObjLib.Application

'(How/what to initialize?)
objPB = ?? 
MsgBox(objPB.ActiveProcessBook.Title.ToString)

'I am using following command to open existing PDI file
objPB.Displays.Open("Actual Path", 1)
objPB.ActiveDisplay.SelectedSymbols.Item(1).AddTrace(sTraceName)

Now my question: Am I using correct class object to find out the active process book and active display from .NET VB code. I am using OSIsoft PB add-in template VB code and trying to achieve this from there. Is there any better way we can achieve this? Thanks.