[Mediawiki-l] Hook function which adds text to the article

[Šerých Jakub]

Hi *,
I would like to call function on AddNewUser hook, which just adds
{{Welcome|username}} text to the users discussion page. 
But I found, that I absolutely know how to write such function. Does anybody
have any example of the function which writes something to the article and
could be called on the hook please?

Thanks a lot

Jakub