Some questions to aid troubleshooting:
What kind of flight controller is it?
What kind of firmware is on the FC right now?
What signal type (PWM, PPM, Sbus, etc.) are you using from receiver to FC?
Have you successfully bound and tested (like with a servo or ESC/motor) the transmitter and receiver?
What kind of computer and OS is it?
Are you aware that you must configure the "arming" and the default is "always disarmed"?
Are you aware that the receiver will not get power from USB and so a battery must be plugged in if you need the receiver to work?