Launching an application (.EXE) from C#?

System.Diagnostics.Process.Start("PathToExe.exe");

Use System.Diagnostics.Process.Start() method.

Check out this article on how to use it.

Process.Start("notepad", "readme.txt");

string winpath = Environment.GetEnvironmentVariable("windir");
string path = System.IO.Path.GetDirectoryName(
              System.Windows.Forms.Application.ExecutablePath);

Process.Start(winpath + @"\Microsoft.NET\Framework\v1.0.3705\Installutil.exe",
path + "\\MyService.exe");

Here's a snippet of helpful code:

using System.Diagnostics;

// Prepare the process to run
ProcessStartInfo start = new ProcessStartInfo();
// Enter in the command line arguments, everything you would enter after the executable name itself
start.Arguments = arguments; 
// Enter the executable to run, including the complete path
start.FileName = ExeName;
// Do you want to show a console window?
start.WindowStyle = ProcessWindowStyle.Hidden;
start.CreateNoWindow = true;
int exitCode;


// Run the external process & wait for it to finish
using (Process proc = Process.Start(start))
{
     proc.WaitForExit();

     // Retrieve the app's exit code
     exitCode = proc.ExitCode;
}

There is much more you can do with these objects, you should read the documentation: ProcessStartInfo, Process.