Found a solution ! ;-)
In "site form" add a dynamic field with this parameter :
- query : construction
- table : #__usergroups
- Options name : title
- Options value : id
this will show you the list of user group
then select "user" has live value (button 2) and in the configuratio put "groups"
Now when you add a new article it will automatically select the right group of the user !
hope it's help ;-)
thank seblod team!!!!!!