If you're new to VB.NET then you should really find some tutorials on the internet or pick up a book. You don't want to be fighting trying to decipher the language while you're also trying to figure out how to use a library.
Your screenshot is all scrunchy, so it's hard to read. However, it seems as if you just have a form with no controls, so you basically want to send a command as soon as the form loads. Hence, the code being in the Form1_Load function. As far as the code, you need to declare the object "GpibDevice". Thus, you need an additional Dim statement:
Dim GpibDevice As Device
That will get rid of the squiggly lines that you see in your code.
Then, your first statement in Form1_Load should be
GpibDevice = New Device(BoardID, PrimaryAddress)
if your device has just a primary address. Otherwise, it would be
GpibDevice = New Device(BoardID, PrimaryAddress, SecondayAddr)
Note that BoardID should be an Integer, not a String, and both PrimaryAddr and SecondaryAddr should be a Byte datatype, not a String. If you keep them as String then you will need to use the CInt and CByte functions as shown in the NI example (see the openButton_Click function).
You can the write your command to the device with GpibDevice.Write(Cmd1). If your device requires a termination character, like a linefeed, then you can just follow the method that's shown in the NI example. There, the command string that's in the textbox has a "\n" to indicate a linefeed as a termination character. A support function is in the example to convert these "escape" characters to control characters. That's the "ReplaceCommonEscapeSequences" function. Thus, the write command would be GpibDevice.Write(ReplaceCommonEscapeSequences(Cmd1)).
Finally, you should close the device with GpibDevice.Dispose().
Thus, your Form1_Load would look like this:
GpibDevice = New Device(BoardID, PrimaryAddress)
GpibDevice.Write(ReplaceCommonEscapeSequences(Cmd1))
GpibDevice.Dispose()
NOTE: Be sure that the NationalInstruments.Common and NationalInstruments.NI4882 assemblies are in your project's list of references. Again, refer to example.
