How should i guide a program to perform correct things? I want to make a small model of A.I. which can learn itself. I am inspired by 1000+ monkey theorem which states that if 1000+ monkey bangs a keyboard for enough long, then they will eventually produce a Shakespeare's play. So, if you give a banana to one monkey when he produce a correct word, then he would eventually learn to do correct things. I think it is related to neural network. 

So, practically i want to start with basic alphabets and digits and then my program would permutate and combine those to form words. Now, if the words they form matches with those in English Dictionary, i want to reward the program. However i couldn't think of any possible approach to this. How could this be implemented?
The "Infinite Monkey Theorem" doesn't say that monkeys will learn.  On the contrary: it says that if monkeys keep typing random stuff long enough (i.e. not using any sort of learning), the works of Shakespeare will eventually come out purely by chance.  It is the Law of Truly Large Numbers.

So you're right: you need to build feedback into the system.  The program should change its behavior based on your feedback.  This is known as reinforcement learning and it is used a lot in AI.  An overarching term for this, I believe, is machine learning.