Master- Slave SPI

I'm working with SPIs. How can a communicate with one of them?
i am using arduino Mega, MFRC522 and SD Card module.

here is the code.

#include <SPI.h>
#include <SD.h>
#include <MFRC522.h>

static constexpr int8_t SSPIN = 53;
static constexpr int8_t RSTPIN = 5;
int8_t csPin = 4;

MFRC522 mfrc522(SSPIN, RSTPIN);
Sd2Card card;
SdVolume volume;
SdFile root;

void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
SPI.begin();

pinMode(csPin, OUTPUT);
pinMode(RSTPIN, INPUT);
pinMode(SSPIN, OUTPUT);

digitalWrite(csPin, HIGH);
digitalWrite(RSTPIN, LOW);
digitalWrite(SSPIN, HIGH);
storage();
RFID();

}

void RFID() {
digitalWrite(RSTPIN, HIGH);
digitalWrite(SSPIN, LOW);
mfrc522.PCD_Init();
mfrc522.PCD_DumpVersionToSerial();
digitalWrite(RSTPIN, LOW);
digitalWrite(SSPIN, HIGH);
}

void storage() {

digitalWrite(csPin, LOW);
if (!SD.begin(SPI_HALF_SPEED, csPin)) {
Serial.println("initialization failed. Things to check:");
Serial.println("* is a card inserted?");
Serial.println("* is your wiring correct?");
Serial.println("* did you change the chipSelect pin to match your shield or module?");
return;
} else {
Serial.println("Wiring is correct and a card is present.");
}
digitalWrite(csPin, HIGH);
}

void loop() {
// put your main code here, to run repeatedly:

}

what is your problem?
have you looked at the examples on line
https://playground.arduino.cc/Learning/MFRC522