Thank you for your quick reply. Here is a screen shot I took from Word 2010. It is a little different but make sure you have selected to "Print two-sided, flip on long edge" selected. Also, if you have not seen the first images I offered before, go to Start Button>>Devices and Printers (on the right)>>Right-click on your printer>>select Printing Preferences>>[make required changes]>>Click Apply.
I know your screens are going to look different than mine but they all use the same words and actions to apply the same functions.
This is an image from Word 2010 after I pressed Print...
I really hope this helps!