Okay, so there are two types of history books you'll see on the market: popular history books ("popular" in this case meaning "for the people") and academic history books.

Popular history books (such as Band of Brothers, by Stephen E. Ambrose, off the top of my head) are for a general reader. They do not assume pre-existing knowledge from the reader, and they don't tend to go very far into the fine details. This isn't to say that they don't contain credible scholarship or advance academic knowledge - generally, they DO - but they are written to be accessible to people who are not already historians.

Academic history books tend to assume a certain level of knowledge from the reader, and are written mainly to advance scholarship of a specific subject. So, the book I'm reading right now, The Rules of the Game, by Andrew Gordon, is about British command and control at the battle of Jutland in 1916, and it is around 700 pages long. It's not for a general reader.

So, to build on our examples, Ambrose's Band of Brothers will tell you what Easy Company in the 101st Airborne did during World War II, but you're not going to see any deep dives as to why battles played out as they did. In contrast, Richard B. Frank's Guadalcanal follows each stage of the battle with an analysis of why it happened, what the mistakes were on both sides, and will go as far as to analyze warship gun sizes in a discussion on whether this made a difference to the result.

This isn't to mean that there isn't overlap between the two categories - there is - but the way that the book tackles the history it is covering is different between the two categories. Popular histories usually tend to concentrate on what events happened; academic histories tend to concentrate on why events happened and what the greater implications are.

Normally, I'd suggest that you go to a physical bookstore (not a university bookstore) and look through their history section to find popular histories, but these are not normal times. So, you're going to need to rely on Google, book reviews, and your own judgement for books selection for the time being.

What I'd suggest regardless, however, is that you start with an overview history book. For example, if you're interested in the Second World War, you get and read a book covering the entire war. While you read that, you will discover areas of the war that you want to learn more about. So, then you should look for books on that particular subject. As you read that, you will find there are details or specific events that you want to learn more about - so you then go and find books on those. What this should do is get you immersed in the topic with sufficient background to know what is going on by the time you get to the more granular/academic stuff.

Greetings. You might want to check out this section of our booklist.

If you have trouble understanding academic books, this post might be of interest to you.

Hope this helps.