firstly make threads.
ThreadStart t1=new ThreadStart(Threadname1);
ThreadStart t2=new ThreadStart(Threadname2);
ThreadStart t3=new ThreadStart(Threadname3);
Thread th1=new Thread(t1);
Thread th2=new Thread(t2);
Thread th3=new Thread(t3;
th1.Priority=ThreadPriority.High;
th2.Priority=ThreadPriority.;
th3.Priority=ThreadPriority.normal;
th1.Start();
th2.Start();
th3.Start();