From Solution Explorer, right-click on the TestMakerFreeWebApp project and select Manage NuGet Packages. Ensure that the Browse tab is selected, and then type Mapster into the search box and press Enter. Select the appropriate result and press the Install button to add it.
Ensure that you select a stable version; for the purpose of this book, we'll use Mapster 3.1.1, which is currently the latest stable one. As always, you're free to choose any other release as long as you remember the disclaimer in Chapter 1.
For those who prefer to use the NuGet Package Manager Console, here's the one liner:
PM> Install-Package Mapster -Version 3.1.1