Actually I do understand the difference between it's and its... "its" denotes ownership (genitive case), "it's" is a contraction. It is a rare circumstance and I am embarrassed for a brit who doesn't understand it. Seriously, that is really embarrassing, even after I gave you a dictionary entry showing that I was correct in usage and that you are flat wrong.
http://dictionary.reference.com/browse/it
it
[it] Origin Like this word?
it
1 [it] Show IPA pronoun, nominative it,
possessive its or ( Obsolete or Dialect ) it, objective it; plural nominative they, possessive their or theirs, objective them; noun
pronoun
Now please, get yourself a better grammar coach because you don't have this one right.