Roles and permissions

Hi everyone! I think that he ask for more or less the same as me...

I'm new in moodle, and I've just aquired the Administrator role.
I 'm make a login access for specific users based on their language (for example login.php?lang=en) and I created a user for each language. Then, when someone log in using this users (spanish, english, italian, etc.) I want that they only see the courses where this kind of users are enroled in...I've created the same courses whit the same contents but in this diferent languages, and I have enroled the user "spanish" into the courses in spanish language, the user "english" into the courses in english language, etc. and then I want that the user "English" can only see at the Front Page the list of courses in english, not to see also the courses in spanish, italian etc...
can anybody help me...?

I don't know if I someone would understand what I'm asking for, but thanks for your help either.

Joel