i will read the two docs you linked to (if i find the strength to spend my afternoon reading something i absolutely don't understand) but, you speak of my "server" , as i told, i'm not on any server, i'm working local with xampp...
i'll post the htaccess.txt but i don't understand: before installing joomsef, i have only one file called " htaccess.txt", and when i install joomsef, there's another htaccess called " .htaccess" (DOThtaccess no extension) that appears, while the htaccess.txt stays there.... which one do you want?
also, as far as i know, the mod_rewrite was enabled in the joomla global parameters. and i don't understand what you mean by "the .htaccess file is allowed to be used in the web site's directory."