For Interacting with system Processes,like start or kill process,.Net provides us with the namespace System.Diagnostics.
System.Diagnostics namespace contains a class Process which provides the functionality to monitor processes connected across a network as well as the local machine
Running another exe file

System.Diagnostics.Process.Start(“pathofexefile”);
System.Diagnostics.Process.Start(“notepad.exe”);

Killing a currently running process

Process[] processes = Process.GetProcessesByName(“googletalk”);
foreach (Process p in processes)
{
Process.GetProcessById(p.Id).Kill();
}