Basically the text in red says that unless you are drawing the card you would normal draw during your draw step, you need to discard a card instead-this action is a replacement effect, the discard replaces the act of the draw.

The blue text basically says if you did this replacement effect, you can now draw a card-note the "this way" after draws a card it refers to the replacement effect-discarding via one with nothing or any other discarder has nothing to do with the replacement effect therefore you do not draw

the b;lack text basically says that if you did not discard (do the replacement effect) you mill yourself 1 card

 

Hope that clears it up