A Bbook (In the US we capitalize The first and Last words of a title, and then any word in the title that is not a preposition)

Long ago, I read a book about two children who lived during a war. They explained told how their childhood was, and, to tell the truht truth, their lives were not easy. (explained sounds much more natural; truth was a spelling error, and the comma after "and" was not needed: ...., and to tell the truth, ....)
They couldn't go atto school, in spite of they wanted to go (a few ways to say this: even though they wanted to go; in spite  of the fact that they wanted to go), and this makes me think about the children who live in the so called "first world" which (we don't usually use which to refer to people, better word to use would be who) often don't want go to school., they don't know, obviously, how lucky are they. They obviously don't know how lucky they are.

I have always read a lot of books , however, since the internet arrived at  in my life, I spend a lot of time reading other things, indeed, I have three or four books half read. ( Since you are still reading, just not books, you need to clarify in the first part of your sentence. Also, most people where I live would add "on the shelf" or something like that to the end of your sentence).