In Reaktor terminology, "macros" are functional blocks that make the construction of complex structures quite easy. Keep in mind that Reaktor supports two kinds of macros: Primary (macros that reside within the primary level of the program) and core macros (which - no surprise - reside within the core level of the program). Don't worry, the user manual explains the difference, and why you'd choose one over the other. Reaktor comes with an extensive library of macros to get you started. When you're ready to construct your very own synthesizer, you'll use macros - for example, if you want to use a 4-Pole filter. Think of macros as your building blocks, but also keep in mind that unlike hardware designs, you're not locked into a preset signal chain. Don't forget to save as you go, so that later, you can go back to a particularly interesting sound and take it in an entirely different direction.