how to detect a specific letter from a strint python code example

Example 1: how to check if a string contains a word python

if word in mystring: 
   print('success')

Example 2: how to search for a specific character in a part of a python string

myString = "God is good"

if "o" in myString[0:4]
	print("Working! There is an 'O' in between the G and D of God.")