I'm pretty sure it should be "abres el libro" if you're talking about someone else opening a book, "abren el libro" would refer to many people opening books and "abro el libro" would mean you yourself would be opening the book.
You're writing<span> a </span>family newsletter<span> to </span>let everyone know what's going<span> on with </span>your family members<span>. </span>Choose three family members<span> and </span>write 2-3<span> </span>