Have you ever worked with midi before? You really didn't give enough information so imma just say some general things about midi.
Midi does not transmit sound. So you need a interface to run midi cables to your keyboards midi in and midi out plugs as well as audio in from your keyboard.
Your midi device that connects midi to your keyboard should have drviers for it, if they are installed correctly, you should see it in your midi setting under remote control input in FL.
For short, under your option tab, you need to enable everything midi.
Your midi will not work in FL if you do not set a port number, mine is set to zero.
I'm sure someone else will pick up the peices I've left out. Good luck, and give us more info next time.