To start on Arduino, nothing like flashing a LED! In this mini-tutorial, I show the programming part of the Arduino and I explain the electrical diagram: Why do you need a resistor? What value should I choose for the resistor?
Temperature and humidity sensor
Retrieving a physical quantity such as temperature with an Arduino is very simple with a DHT11 or DHT12 sensor. I explain how to wire the sensor and use the Adafruit “DHT sensor library” to create a simple program and retrieve sensor data.