There are many books available to read through for screenwriting, cinematography, editing, sound design, etc.
The best online "school" in terms of value seems to be lights film school.

What resources do you know for doing a course, either online or through DVDs ?
By a course, I mean a planned schedule, sample footage, etc.
I was especially interested in sound design in post, as there are limited options for "learning by doing".

I have a lot of footage taken for my film, but now I'm stuck trying to design the sound and editing properly.

I of course am being self-serving here, but at the link in my sig you'll find award-winning DVDs on lighting and sound. Many who have used them have raved.