Question about iron on transfers..

[shoppgirl]

I would like to make my own personalized tshirts for our upcoming trip. I got some great designs from Kellybell! However, I am at a loss as to how to print them onto the iron on transfers!!!!! I know I have to "flip" the design before printing onto my ink jet printer. I have read and researched on line how to "flip" the image on Microsoft Word, but every time I go to do it, the "Flip Horizontal" is greyed out and I can't select it!!! Does anyone know why? Can anyone offer some tips on how to print the designs onto the transfer paper? I would appreciate any tips! Thanks in advance.