The full documentation about Urbi script is in part II of Urbi sdk.
All script commands shall be preceed by "Global.moduleName."
To call a function from the API :
Global.moduleName.functionName
example : 
var a="bonjour";
Global.tts.say(a);
To use a var from the API :
Global.moduleName.varName
example : 
Global.servo.leftEyePan = 50;

Tutorial

You can find a tutorial file in your Reeti : /home/reeti/Devel/Samples/Urbi/script/
You can also see it online : Urbi Script Tuto
This tutorial gives some simple samples for each Urbi functionality.
To "execute" the tutorial :

How to run my Urbi script

You can run urbi script in several ways :

  1. Manual local execution :
    1. Enter urbi commands in an Urbi console (shortcut on Reeti Desktop)
    2. Load a script file in Urbi console : load("/mypath/myScriptFile.u");

  2. Automatic execution at Reeti launch
    1. At Reeti power on, 3 script files are loaded in Urbi :
      1. /home/reeti/reetiPrograms/load/functions.u
      2. /home/reeti/reetiPrograms/load/initVar.u
      3. /home/reeti/reetiPrograms/load/neuralBlocks.u
    2. You can add any urbi script in those files. You can load your own script files from those files. 
    3. The 3 differents files are intended to separate script in categories : basic functions, variables initializations and AI functions. However the 3 files are loaded in the same way and you can add whatever you want in each one.

  3. Send script to Urbi server through IP connection

    1. From any language or any TCP/IP client application, you can send Urbi script to the Urbi server on port 54001 

    2. Using netcat : 

      1. open a terminal

      2. netcat 127.0.0.1 54001   (or external Reeti IP address for a remote connection)

      3. enter your command : Global.tts.say("hello");

    3. Using netcat in command line : echo "Global.tts.say(\"hello\");" | nc -q1 127.0.0.1 54001

    4. Using Urbi C++ client : refer to 

    5. Using Urbi Java client : refer to 

    6. Using any other language TCP/IP client : refer to your language manual to create a client on 54001 port and send string containing your Urbi script.