string strCmdText = "/C copy /b Image1.jpg + Archive.rar Image2.jpg";
System.Diagnostics.Process.Start("CMD.exe",strCmdText);

This is to hide the cmd window.

System.Diagnostics.Process process = new System.Diagnostics.Process();
System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
startInfo.FileName = "cmd.exe";
startInfo.Arguments = "/C copy /b Image1.jpg + Archive.rar Image2.jpg";
process.StartInfo = startInfo;
process.Start();