This lesson covers looping. This is how you write a macro that performs actions repeatedly. The lesson covers the various types of loops and it also has a section explaining what collections are and how they relate to looping. Combining the topic of Mastering Excel Macros: IF Statements and this lesson gives you a solid foundation you can use to build more complex macros. Now you can add logic to a macro (covered in Book 4) and repeat that logic as often as needed (this lesson)
As usual, the lesson comes with several follow along workbooks that you can use to work through the exercises at your own pace. You can download the follow along workbooks by signing up at my website and you will receive an email with the files: http://markmoorebooks.com/macros-looping/
Note these lessons are for Excel for Windows. The screenshots are of Excel 2013 but the code should work for versions of Excel 2007 and forward.