Beginner String formatting question

[JAMoore84 at gmail.com]

Hi all,

I am trying to write a simple program that will accept an integral
"time" input in the HHMMSS format and output a "HH:MM:SS" form.  My
code is as follows:
========================
import string

def FormatTime(time):
  '''Converts an HHMMSS string to HH:MM:SS format.'''

  timeString = str(time)  #converts the num to string

  hours    = [timeString[0], timeString[1]]
  minutes = [timeString[2], timeString[3]]
  seconds = [timeString[4], timeString[5]]

  Ftime = "%s:%s:%s",(hours,minutes,seconds)
  clock = Ftime.join()

  return clock
  ===========================

when I run it from IDLE, I get this:

>>> Format.FormatTime(time)
['1', '1', ':', '2', '2', ':', '3', '3']
['1', '1', ':', '2', '2', ':', '3', '3']

My questions-
1) Why is this function printing out twice?
2)It may be a formatting issue, but I want to have the output as
"HH:MM:SS", rather than having it broken out into each cell.  I
thought the 'join' command would do this, but I must not be using it
properly/understanding something.
3)as a side note, I've noticed that the parameter "time" passed in
must be passed in as a string, otherwise I receive an error that
"time" is unsubscriptable.  Am I unable to pass in an int and then
convert it to a string within the function with str()?

I've been at this for a while, so I may not be able to see the forest
through the trees at this point.  I'd greatly appreciate any
suggestions or instruction on these mistakes.

Best,

Jimmy