PLEASE, don't misunderstand me. If you have to ask this question, it's VERY possible (in my mind) that you could be in for trouble if you "don't do the right thing." You may be able to determine a load bearing wall but what do you do after that? Will you be able to 'properly' brace it? Do you know how to properly install a header? Do you know the 'distance' a header can span? And so on?
Do realize this - If you DO miscalculate, and your 2nd floor ends up on your 1st floor, you're going to have a difficult time explaining what went wrong to your Insurance Company. In may cases, a violation of Building Codes MAY void your insurability.
My best to ya and hope this helps.
Jay J -Moderator
PS: I suggest you visit a Book Store and review some of the books to see if they talk about Load Bearing Walls. That way, you can get your info 'in writing'. (Buying a book is a whole, heck of a lot CHEAPER than the repair bill if you mess up.)