A Spell Book, a Book of Shadows, a Magical Hoard. This can be called by many names. Since you say you do not know much about spell casting, I would always recommend studying before performing, these studies can be writen into your selected book, notebook, binder (it's up to you).
As you learn the basics, so spell casting will become easier, but writing down a bunch of spells you have no idea on how they function isn't really going to make your book any helpful.
Learn the laws, the rules of magic, and the basics that can help your craft take place.