USB device interface examples?

I do have some documentation for the driver.

There are 4 routines that are available:

Public Function Load_drv(ByVal mySN As String) As Boolean
Public Sub Get_Det_Reading(ByVal Freq_GHz As Double, ByRef Det_dB As Double, ByRef success As Boolean)

Public Function Unload_drv() As Boolean
Public Function Check_Status() as Boolean

There is a brief description of what each routine does.

I'm thinking that the details that I really need are coded into the .dll file that gets called when I use any of those functions.