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What version do you have of IDE? In newer versions, you install the MySensors library in IDE

//Mattias

@DannyM

Yes you can use LDR and a DHT11 together.

 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * REVISION HISTORY
 * Version 1.0 - Henrik EKblad
 * 
 * DESCRIPTION
 * Example sketch showing how to measue light level using a LM393 photo-resistor 
 * http://www.mysensors.org/build/light
 */

// Enable debug prints to serial monitor
#define MY_DEBUG 

// NodId
#define MY_NODE_ID 99

// Enable and select radio type attached
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69

//Including nescessary libraries
#include <SPI.h>
#include <MySensors.h> 
#include <DHT.h>  

// Set this offset if the sensor has a permanent small offset to the real temperatures
#define SENSOR_TEMP_OFFSET 0

// Sleep time between sensor updates (in milliseconds)
// Must be >1000ms for DHT22 and >2000ms for DHT11
static const uint64_t UPDATE_INTERVAL = 60000;

// Force sending an update of the temperature after n sensor reads, so a controller showing the
// timestamp of the last update doesn't show something like 3 hours in the unlikely case, that
// the value didn't change since;
// i.e. the sensor would force sending an update every UPDATE_INTERVAL*FORCE_UPDATE_N_READS [ms]
static const uint8_t FORCE_UPDATE_N_READS = 10;

//Defining child ID
#define CHILD_ID_LIGHT 0
#define CHILD_ID_HUM 1
#define CHILD_ID_TEMP 2

//Defining Pin
#define DHT_DATA_PIN 3
#define LDR_PIN A0

//Defining values to store sensor information
float lastTemp;
float lastHum;
uint8_t nNoUpdatesTemp;
uint8_t nNoUpdatesHum;
bool metric = true;
int lastLightLevel;

//Defining sleep and wait times
unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)(30 seconds)
#define MESSAGEWAIT 500

MyMessage LightMsg(CHILD_ID_LIGHT, V_LIGHT_LEVEL);
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
DHT dht;

void presentation()  {
  // Send the sketch version information to the gateway and Controller
  sendSketchInfo("Temp Fukt Ljus", "1.0"); // 2017 02 05
//  wait(MESSAGEWAIT);

  // Register all sensors to gateway (they will be created as child devices)
  present(CHILD_ID_LIGHT, S_LIGHT_LEVEL);
//  wait(MESSAGEWAIT);
  present(CHILD_ID_HUM, S_HUM);
//  wait(MESSAGEWAIT);
  present(CHILD_ID_TEMP, S_TEMP);
  
    metric = getControllerConfig().isMetric;

}

void setup() 
{
  dht.setup(DHT_DATA_PIN); // set data pin of DHT sensor
  if (UPDATE_INTERVAL <= dht.getMinimumSamplingPeriod()) {
    Serial.println("Warning: UPDATE_INTERVAL is smaller than supported by the sensor!");
  }
  // Sleep for the time of the minimum sampling period to give the sensor time to power up
  // (otherwise, timeout errors might occure for the first reading)
  sleep(dht.getMinimumSamplingPeriod());
}

void loop() {
  // Force reading sensor, so it works also after sleep()
  dht.readSensor(true);

  // Get temperature from DHT library
  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
    Serial.println("Failed reading temperature from DHT!");
  } else if (temperature != lastTemp || nNoUpdatesTemp == FORCE_UPDATE_N_READS) {
    // Only send temperature if it changed since the last measurement or if we didn't send an update for n times
    lastTemp = temperature;
    if (!metric) {
      temperature = dht.toFahrenheit(temperature);
    }
    // Reset no updates counter
    nNoUpdatesTemp = 0;
    temperature += SENSOR_TEMP_OFFSET;
    send(msgTemp.set(temperature, 1));

    #ifdef MY_DEBUG
    Serial.print("T: ");
    Serial.println(temperature);
    #endif
  } else {
    // Increase no update counter if the temperature stayed the same
    nNoUpdatesTemp++;
  }

  // Get humidity from DHT library
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
    Serial.println("Failed reading humidity from DHT");
  } else if (humidity != lastHum || nNoUpdatesHum == FORCE_UPDATE_N_READS) {
    // Only send humidity if it changed since the last measurement or if we didn't send an update for n times
    lastHum = humidity;
    // Reset no updates counter
    nNoUpdatesHum = 0;
    send(msgHum.set(humidity, 1));

    #ifdef MY_DEBUG
    Serial.print("H: ");
    Serial.println(humidity);
    #endif
  } else {
    // Increase no update counter if the humidity stayed the same
    nNoUpdatesHum++;
  }

  
  int lightLevel = (1023-analogRead(LDR_PIN))/10.23; 
  Serial.println(lightLevel);
  if (lightLevel != lastLightLevel) {
      send(LightMsg.set(lightLevel));
      lastLightLevel = lightLevel;
  }
  sleep(SLEEP_TIME);
}

LDR pin A0

DHT pin 3

And i use pro mini.

//Mattias