Check out example codes for "c# error messagebox". It will help you in understanding the concepts better.

Code Example 1

MessageBox.Show("your message",
    "window title", 
    MessageBoxButtons.OK, 
    MessageBoxIcon.Warning // for Warning  
    //MessageBoxIcon.Error // for Error 
    //MessageBoxIcon.Information  // for Information
    //MessageBoxIcon.Question // for Question
   );

Code Example 2

MessageBox.Show("text", "title", MessageBoxButtons.OK, MessageBoxIcon.Warning);

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