if u need more details please tell me.
I think the following thread lays out the steps for doing what you want. If it doesn't help, let us know:
Thank you for your help it was exactly my case and what you provided was useful,
but i need one more little tip !! should portal records fields be implemented in a table so i could manage to define tests on them and perform group actions on them ???
That would certainly be convenient. You can hide such utility layouts from users so they don't have access to them except through a portal you've placed on a different layout. Filemaker makes this easy for you in that it automatically creates one layout for each table at the time you first create the table. That can be your utility layout for this job or you can create a new layout for the purpose.