Hi,
Online heavy metal lessons will teach you how to get the right sound, and also the various techniques required to enable you to increase your playing speed. You will learn hammer ons that allow you to play more that one note with a single pick of a string, and various other techniques such as vibrato and spider walking around the frets, that not only helps with the flexibility and strength of your fingers, but also enables you to play single notes pretty fast.
The most useful tool for you, however, is the pentatonic scale.
