You can use NotifyIcon
for this.
this.WindowState = FormWindowState.Minimized;
notifyIcon.BalloonTipIcon = ToolTipIcon.Info;
notifyIcon.BalloonTipTitle = "Notify Icon Test Application";
notifyIcon.BalloonTipText = "You have just minimized the application." +
Environment.NewLine +
"Right-click on the icon for more options.";
notifyIcon.ShowBalloonTip(5000);
This will generate popup like one as below:
You can find more details on this link.
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