Summary
If you are fairly new to building on the web, you almost have an advantage when it comes to learning CSS Grid; a "beginner's mind" if you like. For people that have been laying things out with other techniques over the years, the difficulty, in some ways, is undoing what you already know about layout with CSS.
Having read this chapter, you should have some understanding of what is possible with Grid and how you might employ it.
Furthermore, if you were in any way successful with the exercises, you should congratulate yourself; there's a lot to consider when you first start using Grid. If you accomplished something with your first effort, you did admirably.
At this point, I'll also reiterate that Grid is tricky at first. It comes with a lot of possibilities but also quite a few new pieces of terminology and concepts. Expect to take a few runs at it the first time you use it. But I promise that, once you get competent, it will pay...