Hi, i create my users, my user's groups and my categories and when I create a new item, i can't see my users in the Author list ( only administrator in there...)Is this normal or did i miss something?Thanks

On the user groups what settings have you assigned to each one? Maybe the users that you are trying to see on the authors list have no permissions to add items and that is why you can only see the Administrators.

Thank you for your answer.
Users are "registred". These users can create an item on front end of the site but i can't assign an item to these users in the back end.
The reason i do this is because I want "registred users" see their own items on front end and edit them and I want "special users" see all the items. But at first, i have to create all the users and load the first item for each one. It's easier if I do this in back end ( I can copy the items... )
I don't know if it's understandable because my english is not so good.

There are some user groups that are not able to access the backend, and therefore you cannot assign to them items, and those are: Registered, Author, Editor, Publisher. These have only frontend editing permissions. You can read about them here: help.joomla.org/content/view/228/153/1/1/ to understand more.

Thank you for your answer.
I will have to edit each item on front end.... quite long ...but possible.

Best regards