From a certain English word, I would like to know how many steps, which is the minimum number of elementary operations, I will have to make so as to come to the last word which has been predefined. Each time I make a move, there is only one character in the sequence being allowed to change. To be more concrete, for instance, I have a term called cooler, first I will have to try changing it into fooler, and then foller, again feller, one more time fellor, and finally fellow which is the final word I am looking for, and I have already made five moves after all.
Could you give me your ideas, advice, comments etc, on how to accomplish this ? Please help...

Thank you very much...
Nina.