Hi Sidney,
To get the 727-200 or the freighter for FSX, if you already have the 737-100, you can buy the upgrades as expansion packs.  If you don't have the 727-100 you can get the 727 Captain, which has all of the models -100, -200 and Freighter.  http://www.captainsim.com/products/x727/

When you click on "Buy Now" you will be asked to select how you will be purchasing it.  Choose how and you will be taken back to the store where you will see icons of the products.  Make sure you choose 727 Captain from the second row of icons if you don't already have the -100.
If you have the -100 then choose the "More Info" link on the 727-100 Pro Pack and scroll to the bottom where you will find the links for the -200 and Freighter.