What process do people go through to solidify their understanding of something they have read?

What do the excerpts have in common? both point out the tragic nature of situations in which children make journeys without their parents. both describe what immigrant children must do to survive when traveling to the united states. both explain why most children want to leave central america without their parents. both indicate the tragic problems and their consequences that children in central america must face.

"such has been the patient suffrence of these colonies; and such is now the necessity which constrains them to after their former systems of government. the history of the present king of great britain is a history of reapeated injuries and usurpations, all having in direct object the establishedment of an absolute tyranny over these states." which statement best describes the excerpt

I'm currently writing a book. do you have any good tips for that?