What is the most logical next event?

How to earn a black belt
Sign up for a class.
Some people think it is okay to study martial arts from a book, but it is not the same. An authentic school is preferable, but the important thing is to be in a class with good teachers.
There are a litany of techniques you will learn to earn a black belt in karate. You will earn your way up the belt ladder, earning different color belts as you make your way to the black belt.