Start with Robin2's excellent simple rf24 tutorial if you want to use the rf24 radios. >> Simple nRF24L01+ 2.4GHz transceiver demo If you follow the tutorial, closely, you should have success.
An alternative to the rf24 is the HC-12 radio modules. Easier to use and just as much range. >> Arduino and HC-12 Long Range Wireless Communication Module - How To Mechatronics
I have used the RF24 modules for years. But they seem to be very difficult for some to use. They are finicky about power and use several pins. The HC12 use only 2 pins (a serial port, hardware or software).