What I asked was how to fix it. All that would happened by default if you would have used the article submit workflow where it asks if any download to be attached.
About code blocks, you need to always wrap it with a pre tag with a defined language to get proper colorization. You don't need to know any class or style. Put few line of code, select them and use 'code -> C#' for C# code lines. It will automatically apply the need HTML with attribute if any.
Since, I could not edit your article, I suggested you a way to do it yourself.