how code the Authorise.net reaccuring process...

[eluser]pistolPete[/eluser]
Although I didn't really understand what your question is, here are some results of my search:

http://www.merchant-account-services.org...illing-api
http://www.ventanazul.com/webzine/articl...-php-class

Also try the forum search for "Authorize.net", there are a couple of threads of how to integrate Authorize.net into CI.