You can use the below script to search for a specific folder. This will search recursively through the tree.

Set TreeMgr = TDConnection.TreeManager
Set oRoot = TreeMgr.TreeRoot(''Subject'')
Set folder = oRoot.FindChildNode(''MY_FOLDER'')

If folder Is Nothing Then
MsgBox ''MY_FOLDER does not exist.''
Exit Function
Else
MsgBox ''Found it.''
End If

Set folder = Nothing
Set oRoot = Nothing
Set TreeMgr = Nothing