Download the Arduino environment
Download the last version of Arduino IDE from the download page. When the download finishes, double click the downloaded file to install it.
Launch the Arduino IDE
Double-click the Arduino application.
Note: The language will be the same of your operating system.
Connect the board
Connect the Arduino board to your computer using the USB cable.
The green power LED (labelled PWR) should go on.
Open the Blink example
Open the LED blink example sketch: File > Examples > 1.Basics > blink.
This is the example:
Select your board
You'll need to select the entry in the Tools > Board menu that corresponds to your Arduino.
Select your serial port
Select the serial device of the Arduino board from the Tools | Serial Port menu. This is likely to be COM3 or higher (COM1 and COM2 are usually reserved for hardware serial ports). To find out, you can disconnect your Arduino board and re-open the menu; the entry that disappears should be the Arduino board. Reconnect the board and select that serial port.
Upload the program
Now, simply click the "Upload" button in the environment. Wait a few seconds, you should see the RX and TX leds on the board flashing. If the upload is successful, the message "Done uploading." will appear in the status bar. (Note: If you have an Arduino Mini, NG, or other board, you'll need to physically present the reset button on the board immediately before pressing the upload button.)
A few seconds after the upload finishes, you should see the pin 13 (L) LED on the board start to blink (in orange). If it does, congratulations! You've gotten Arduino up-and-running.