OK, IF!! You have two servos then turn on your radio, push the button that says Mode/Page, at the bottom of the page it says reverse, roll the cursor until the reverse highlights, open this up by pressing the roller that says PRESS. On the right of the screen all your channels come up. Roll the cursor until one of the two Chanel's you are using for the flaps is highlighted, reverse it by rotating the knob until it says NOR or REV, try thew flaps on your plane, if they are both now going up then put that channel back as it was and go reverse the other channel.
If you only have the one servo it has to be done like Villa said. Some people use Y-Harnesses, not needed with your 9-C but if you have one then you may want to buy a reversing Y_Harness.
Hope this is of help. If you go onto the Futaba web site all this is mentioned in the FAQ section and it is in your instruction manual.