How to open the system tray aplication

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C#

Hi

i am working with c# windows application.
My application is mainly used to export the excel file.,at a certain time.
The user choose the time then every day i want to extract the file at the certain time.
for this purpose i want to run the application always.so when user close the application it will
go to system tray.myProblem is my application is in system tray then the user click on shortkey of my app it will creating the new instance. so new application is opening and existing app is in system tray. so there are two system tray icon is there.so how to open the existing app from system tray