Difficult to search and it's not in the manual.
I'm using a Mac and can't figure out how to use books.
e.g. Light Armour. I have the book, read it and still don't have Light Armour skill.

If a book does a teach a skill then right clicking to read is all thats required to learn it, not all books teach a skills though, is one your trying to read titled something like "Guide to Light Armour Materials"?, if so this is not the book that gives the skill.

See this post for a list of which books teach what.

Thank you for the help.

And if your Mac does not have a two-button mouse attached, you need to use Cntrl-click to simulate a right-click.

Yes, the "Guide to Light Armor" doesn't actually improve your Light Armor skill. "Scout's Guide to Defensive Attire" does. Funny how that works.