When I first started programming, I was in my mid-twenties. I started a lot older than most, but I will say that grasping the basics took me a bit longer than most, too. I remember when I bought my first programming book, and I read and re-read chapters over and over again until the concepts made sense to me. I found that a lot of books talked to me like I had majored in computer science. As you progress through this book, take your time and, if you need to go back, it is okay to do so. No one is going to care that it took you an extra day to understand a concept. It is more important that you fully understand that concept.
One tip I would give you is to not copy and paste the code. No matter where you find the code and no matter how long it takes, it benefits you to type it out. Doing this benefited me, as I eventually started to remember the code, and it became...