Lol I have done it in a much easier way. Tell me if this method is good:

I made the main template, and I put no content in the left column except

@RenderSection("left")

Then I made a new template, which runs of the main template, then in the new template I  put:

@section left{

HTML
CSS
VB

}

then for the default page, I linked that to the new template I made. Then for the HTML pages, I made a new template (_HTML) made the @section left{}  different and it worked! Rendered different content.