Connect/Disconnect to Wireless Network?

Hello all, I was hoping one of you experts could help me. I'm trying to
find a way to connect to a specific (I only have one) wireless network
and then disconnect from it. Basically, I don't want to be constantly
connected to the web, but only when I need to be, like when I open
firefox or ie. I figured this would be a simple program, but I can't
figure out how to open and close the connections.

Something like:

OpenConnection(); //Don't know how to do this
Process p = Process.Start("firefox.exe");
p.Wait();
CloseConnection(); //Dont' know how to do this either :-)

Does anyone have any good links or sample code for this?

Thanks for your time!