Modify properties of content using rule

[mannobug]

Hi all i'm new in Alfresco develop and i have a little trouble.
I need to set using a javascript rule (or any other way if there is) content metadata when are upload in alfresco. So using  arule that execute script i want to set (override) Title, Description, and author information.
Is therre somewhere any examples of this? can someone help me to undesrtand where i can find infomration to write something.
Thanx everybody.
Ema

[zomurn]

document.properties["cm:title"]="my_title";
document.save();

etc.for other attributs

[mannobug]

Thx zomurn i'll try your sample but it doesnt wirk using  your code.
I wrote a script saved in Scripts under Data Dictionary, wrote a rule over all inbound contents to execute a script.
When i check propoerties of file just loaded  author and title are "admin" and the name of the file.
Where i can debug it? Where i can find this information?
Thax all.