private void button1_Click(object sender, EventArgs e)

        {

             var openFileDialog=new OpenFileDialog {Filter = @"Zip Files|*.zip|RAR Files|*.rar|All Files|*.*"};

            if (DialogResult.OK == openFileDialog.ShowDialog())

            {

                File.Copy(openFileDialog.FileName, Application.StartupPath + @"\" 

                    + Path.GetFileName(openFileDialog.FileName));

                yourvariable = Application.StartupPath + @"\"

                               + Path.GetFileName(openFileDialog.FileName);

            }

        }

your file will be copied to yourprojectname\yourprojectname\bin\Debug