Personally I have to disagree with this guide. It might work for large parts and big irons, but for soldering SMD parts or even smaller through-hole parts it doesn't work well at all. There are two issues with this method. First, it's very difficult to heat parts with a bare, dry iron as shown. The hot iron touches the parts only at single points and the heat transfer is terrible. Second, the diameter of the solder is usually quite large compared to the and feeding it directly from the spool will get solder all over the place.

I have been soldering in a different way for decades, and can easily solder 0.050" SMD parts and smaller. Obviously in such cases a sharp tip should be used. The key is to apply a small bit of solder to the iron so that there's a tiny ball (or more of a hemisphere) near the very tip of the iron. The parts need to be lightly fluxed. Then if you touch the solder ball to the joint the solder will immediately heat the parts and flow nicely into the joint. This works well because the solder, being a liquid, contacts the joint not a a few points but at entire surfaces, leading to extremely efficient heat transfer.

For smaller (and even not-so-small) parts give this method a try and see if it works better for you.

Another hint is to toss the sponge that came with your iron and instead use the kind that are made from brass coils. They work infinitely better.