One point is that speed reading is done by scanning large sections of text. To describe how you do it would take a book but as simply as I can...
You start to read as a child, with one letter at a time, learning to put them together into words.
Once you can read words you scan more than one and don't need to actually identify every letter to recognise a word or short phrase.
To get faster you scan larger and larger chunks at a time, and if you continue this process you can really motor along taking in paragraphs at one go.
This is too simple but gives you the idea.