DFA creation from string
Constructors should be class methods

Your method suggests, that an instance of the respective class is being created using the given text.
Thus you should make it a classmethod:

@classmethod
def create_from_text(cls, text):
    …


Comments vs. docstrings

Your multi-line comment describes the underlying algorithm.
You should summarize it in the method's docstring and move the complete description to your respective documentation docs.

Useful comments

This is useless:


# Easiest part, just set the transition to the next state
# Now do that check we spoke of earlier


while that may be helpful:


# Make every transition in the last state point to itself


Loop variables

While the i in for i in range(len(text)) is pretty self-explanatory, the j in for j in self.alphabet: is not.
What is j? Another index? A word? A character?
Consider renaming j to index, word or char respectively.

PEP 8

You follow it consistently with the exception of self.addTransition.

Iteration over strings.

Instead of

for i in range(len(text)):
    …
    if j == text[i]:


Use enumerate:

for index, char in enumerate(text):
    …
    if j == char: