I'm going to read ‘The Art of War,’. I had first heard about this book beforea bit ago but I didn't want to read it because I thought that this book it was only for soldiers, businessmaen and businesswomen.

- the use of apostrophes makes it more clear that it is a book

However I watched a video about a boy who overcame his addiction to social media using some concepts ofrom this book.

I also watched a video about a girl who also used the concepts of this book, but forto instead achievinge good grades in her exams, instead.

Word order is more natural like this !

I'm going to read it and maybe I couldwill be able to use some of the concepts for my own purposes.

I'm going to read The Art of War,. I had heard about this book before but I didn't want to read it because I thought that this book it was only for soldiers, businessman and businesswomen.

However I watched a video about a boy, however, who overcame his addiction to social media using some concepts ofdescribed in this book.

I also watched a video about a girl who also used the concepts ofdescribed in this book, but for achieving good grades in exams, instead.

I'm going to read it and maybe I couldan use some concepts for my own purposes.

I'm going to read The Art of War, I had heard about this book before but I didn't want to read it because I though that thise book it was only for soldiers, businessman and businesswomen.

I also watched a video about a girl who also used the concepts of this book, but forto achievinge good grades in exams, instead.

I'm going to read The Art of War, I had've heard about this book before but I didn't want to read it because I tough that this book it was only for soldiers,helpful for members of the military, as well as businessmaen and businesswomen.

However, I watched a video about a boy who overcame his addiction to social media using some of the concepts ofrom this book.

I also watched a video about a girl who also usapplied the concepts of this book, but in her case for achieving good grades ion exams, instead.

I'm going to read it and maybe I could'll be able to use some concepts for my own purposes.

I'm going to read The Art of War, I had heard about this book before but I didn't want to read it because I thought that this book it was only for soldiers, businessmaen and businesswomen.

businessmEn - plural
"though" means despite
"thought" is the past tense of think that you were looking for

However, I watched a video about a boy who overcame his addiction to social media addiction using some concepts of this book.

More common to say "(addictive substance) addiction"
Yours work too!

I also watched a video about another girl who also used the concepts of this book, but for achieving good grades in exams, instead.

You won't want to repeat "also" twice, so consider using "another"