I guess you really are excited because you bought a linear actuator, not a servo. And the servo does not have limit switches so your program can determine when it is fully extended or fully retracted. You best investigate how you will add limit switches to your mechanism. You may also need to use a relay to control the actuator direction and a relay to turn the power on and off.
I suggest you first work on getting the actuator working with your Arduino and separately get the RFID working before combining the two into one program.
Paul