Password Guesser Project

[RedSkeleton007]

one is guest and the other is guess

But I have a new problem:

#!/usr/bin/env python3
#PasswordGuesser.py

AlphaNum = "abc"
passwordThatNeedsToBeGuessed = "cab"
guessMatches = False
guess = ""
guessList = list(guess)#make a list version of guess, so we can change the chars
guess = ''.join(guessList)#convert to a string, so we can print guess as a string
guessLength = len(guess)

##def iterateAlphaNum():
##    i = 0
##    while i < len(AlphaNum):
##        guess[0] == AlphaNum[i]
##        i += 1

guessLength = 1 #start with a guess length of just one char
char1 = 0 
for char1 in AlphaNum:    
    guessList[0] = AlphaNum[char1]
    char1 += 1    
    print(guess)

Error:
Traceback (most recent call last):
  File "I:\Python\Python36-32\SamsPrograms\PasswordGuesser.py", line 21, in <module>
    guessList[0] = AlphaNum[char1]
TypeError: string indices must be integers

I also tried putting the int keyword before char1 on line 19, but an error said that was invalid syntax. This is a problem, because it's vital for this program to be able to dynamically reference chars from AlphaNum.