Give each section some space.. as with code, indentation will make your content more readable.
Reduce the unnecessary typography.. the titles, body text and code blocks all compete and are inconsistent. There are some great mono-spaced fonts that are part of wider family of type, pick a good font-family and stick to it.
The contrast between the dark-themed code blocks and the body text is just too jarring, you might want to try using a lighter code block or experiment with a darker themed body. A well designed color-scheme like solarized can handle the change of contrast while maintaining harmony. Have a good look at a range of color-schemes and see how you might be able to use one of those colors consitently throughout the site.
Where's the index? I might want to jump to a certain section, or just see what's below without having to skim the whole page.. it's a basic usability feature, but pretty important.
Keep at it, sucking is all part of getting good.