I am having trouble finding out how to get excel VBA to interact with a specific IE Window that is already open.
Here my process:
I open IE, navigate to the
The above code worked well for me. I turned it into a function call as follows
Set ieFindUser = FindIEObject("Find and List Users")            'Find handle for popup window.
The Function
Public Function FindIEObject(target As String) As InternetExplorerMedium
    Set objShell = CreateObject("Shell.Application")
    IE_count = objShell.Windows.Count
    For x = 0 To (IE_count - 1)
        On Error Resume Next    ' sometimes more web pages are counted than are open
        my_url = objShell.Windows(x).Document.Location
        my_title = objShell.Windows(x).Document.Title
        If my_title = target Then 'compare to find if the desired web page is already open
            Set FindIEObject = objShell.Windows(x)
            Exit For
        End If
    Next
End Function
                                                                        Here's what I use. It counts the number of open instances of IE and then steps through each instance and determines the url and title of the web page. You can then compare the title or url against the title or url you are looking for. The following example compares titles using the "Like" function, but like I said you could compare urls if you like. Also, if you are looking for a title or url that doesn't change you can use "=" instead of "Like".
marker = 0
Set objShell = CreateObject("Shell.Application")
IE_count = objShell.Windows.Count
For x = 0 To (IE_count - 1)
    On Error Resume Next    ' sometimes more web pages are counted than are open
    my_url = objShell.Windows(x).Document.Location
    my_title = objShell.Windows(x).Document.Title
    If my_title Like "XYZ" & "*" Then 'compare to find if the desired web page is already open
        Set ie = objShell.Windows(x)
        marker = 1
        Exit For
    Else
    End If
Next
If marker = 0 then
    msgbox("A matching webpage was NOT found")
Else
    msgbox("A matching webpage was found")
End If