This is not simple.
The book reflects in part Microsoft's attempt to move further into the data center. For this, high availability is a must. But the underlying technical implications are intricate. An easy way to see this is to turn to Chapter 2. It describes how to install the cluster that makes high availability via ideas like replication. The GUI that Microsoft offers hints at the many details. Then look at the description of how to do this via the command line prompt. Much more compact than the GUI approach. Yet the verbosity of the command line is impressive, and it shows the fragility of trying to type this correctly.
Going further in Chapter 2, there is the method of installing using an autogenerated Configuration file. It's a flat file, with no (apparent) internal structure beyond 'variable=value' on each executable line. Each variable is minimally documented by a few (well usually just 1) accompanying comment line.
If you compare the Configuration file with the command line example, the latter now seems far too short! It must have assumed defaults for many variables. For the hard core analysts, tweaking the Configuration file may be the best way to experiment with your cluster.
Later chapters go further into more details about how a cluster can be structured. Several types of replication are offered, and the discussion encompasses about half the book.
The chapter about the Log shipping is pretty simple to follow. This is where logs are copied from a primary source to a secondary source, so that the latter can take over if the first fails. Important. But you should spend more of your time on the other, harder parts of the text.
Overview