Here's a simple example: Atoms of iron attract one another and form groups of atoms that stack up and get larger until it gains mass. When enough iron atoms have attracted each other and become bound together, we see it as a piece of iron that a smith can heat, hammer and mold into shapes that we can use, like a horseshoe for instance.
That iron horseshoe looks and feels pretty solid to our senses, but it's really nothing more than a mass of iron atoms all bound together in that shape. And each of those atoms is made up of a tiny amount of physical mass, empty space and the energy created by the motion of the electrons orbiting the central mass or nucleus!
Which Law of Attraction Course Should I Take?
There are a number of very good courses that are available online and well worth your while to take. Different people will naturally have differing preferences as to the course tutor and the material it contains.
My personal choice of tutor is Dr. Joe Vitale, well known meta-physicist and proponent of the Law of Attraction as a way of life. He featured as a presenter in the book and movie, "The Secret" and made a big impression on me personally at the time as well as since with his lectures and books.
More Information
You can read a full length, detailed review of Dr. Joe Vitale's Law of Attraction practitioner certification course that he created in partnership with NLP specialist, Dr. Steve G. Jones by following this link:
https://disciplinedthinking.com/law-of-attraction/joe-vitale-law-of-attraction-certification.php
Of course, the final choice is yours as to which training package you decide to take. There are others and while I'm sure they are very good, I do not have any personal experience with them and so can't expand on their advantages and disadvantages.
I feel that, in my own opinion, if you are going to learn a subject, it might as well be taught by one of the best teachers around. To my mind, in this subject, that teacher is Dr. Joe Vitale, the Law of Attraction expert also known as Mr Fire!