run my code automatically without userInterface

If you do not want a form to be displayed, then you should go for Console application. But, still it is possible for windows forms to run silent.

Go to Program.cs file in your application and comment the 3 lines in the Main() method which starts with Application.

//Application.EnableVisualStyles();
//Application.
//Application.

Write your code here to execute and when you run it will run silently without opening a form.

I have written a simple code to write to a file.

string lines = {"first", "second"}
File.WriteAllLines(@"C:\lines.txt", lines);

Let me know if you any more help.