How can I keep a randomized value of a variable constant in a while loop when certain conditions occur?

I tried to make an basic number-guessing game. However I couldn't find the way that I keep the randomized number constant in order to give clues to user to increase or decrease his/her guess.This is so easy for you but I need your valuable and useful perspectives. PS: Yeah I am a beginner.

 while (true)
        {
            Random rd = new Random();

            Console.WriteLine("guess a number 0-10");

            guess = int.Parse(Console.ReadLine());

            comp = rd.Next(10);

            if (guess == comp)
            {
                Console.WriteLine("congratz!! u won!!");
                Console.WriteLine("press any key to exit");
                break;
            }
            // Those are the conditions for directing user.I couldn't   implement it.

            //else if (guess > comp)
            //    Console.WriteLine("your guess is greater than my number, yow!");
            //else if (guess < comp)
            //    Console.WriteLine("your guess is lower than my number, yow!");


            Console.WriteLine("loser!!" + "My number was:" + comp);
          }
             Console.ReadLine();