Please see my comments to the question. As you did not share your purpose, it's possible only to give a couple of general ideas.
Nothing can happen if the host to be controlled is not running some service code to respond to commands from other host. Basically, you can create a network service in the form of Windows Service. Please see:
http://en.wikipedia.org/wiki/Windows_Service[
^],
http://msdn2.microsoft.com/en-us/library/ms685141.aspx[
^].
Please start here:
http://msdn.microsoft.com/en-us/library/d56de412%28v=vs.100%29.aspx[
^].
You can do networking on several different layers; I overview them in my past answers:
how i can send byte[] to other pc[
^],
Communication b/w two Windows applications on LAN.[
^].
On the server side, you can control the mouse using the Windows API
SendInput, P/Invoked. Please see:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms646310%28v=vs.85%29.aspx[
^],
http://www.pinvoke.net/default.aspx/user32.sendinput[
^].
If you still need to learn P/Invoke, please use see:
http://en.wikipedia.org/wiki/PInvoke[
^],
http://msdn.microsoft.com/en-us/library/Aa712982[
^].
This CodeProject article can also be useful:
Essential P/Invoke[
^].
Again, hard to say if you can use some more specialized approach without knowing your goals, but pay attention for the advice by Björn Ranft in the comments to the question.
—SA
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