you'll need to figure out how to use Python's string manipulation library to convert a string into an array.
str1 = "treehouse"
is a string,
list1 = ["t","r","e","e","h","o","u","s","e"] is a "list" (called an "array" in most languages, not sure about python)
in Java, list[0] is "t", list[5] is "o" (Note that array indexes start at 0 in most languages)
Python might allow you to treat the string as an array of characters without conversion.
i.e. str1[1] is "r" (I think JavaScript works this way)
you really need to learn the syntax of the language (how to do loops, conditional blocks/operators, work with arrays), then learn about the standard libraries (i.e. printing out to the screen, manipulating strings, more advanced math functions)
that's really what's most important.
when I say "most languages" I mean "most languages I've used". heh.