Vigenere Cipher Decryption

[wyndestalker]

I am working on a C++ project that will take a Vigenere ciphered text and make an automatic attempt at the key and decryption of it. I have found a very useful code on a Wiki the problem is it uses concepts I do not know yet. So it is hard for myself to figure out what each part is doing and why since the //comments are not very detailed. I will not know the key or key length for the encrypted text I will need to decipher. I am aware that I will need to use letter frequency to figure it out but unfortunately I just can not visual how to go about it. As far as the class I have been taking the only concepts we have learned is creation of our own classes and very basic <string>, <iomanip>, <iostream>, and <conio.h>. Any help in understanding how I should be looking at this or something to help me figure out how to even start would be greatly appreciated.