Asking yet again about categories

Sorry if this is getting old to some. I just haven’t quite given up hope of getting an answer yet.
I am trying to do something that I would think is simple, but it seems it’s anything but that.
I have a bilingual blog. Seeing the category – sub and sub-sub-category structure available in WP, I figured it would be really simple to split up the display of categories in two on index.php.
What I have done/tried:
I created 2 primary categories, one for each language.
I created sub and sub-sub-categories under those two. In effect, to the visitors, I want them to be seen as categories and sub-categories.
Where I’m stuck is getting them to display as 2 separate lists of categories, each with it’s title, i.e. Français and English.
I tried getting an answer in IRC. Did get directions from Skippy to a page where various category tags are shown. I tried using the exclude, the children and the child_of tags. Nothing changed in the way the lists displayed.
I asked in another thread here about splitting the categories. That got zero answer.
So, I’m giving it one last shot here, before I do what I was doing with MT: just hard-code the friggin categories in the index page.
One last note, and no, I’m not trying to be difficult about it. 🙂 I =am= a newbie. I am =not= a programmer. Until a bit over a week ago, I had never looked at php. So, if someone has suggestions, please be specific. Sometimes I see things like “put this or that at the top of wp-header.php. Well, to me, the top can be anywhere. I don’t have a clue – yet – what I should be looking for, so specifics would be real nice.
Thanks in advance if anyone has the patience to explain.