Copyright is a bundle of rights that artists own in relation to their work. This means artists have the right to do certain things in relation to their creations and no one else has the right to do those things without their permission.
You do not need to register your work to get copyright. You get copyright automatically.
Copyright does not protect ideas. It only protects original works that are made into material form. For example, if you share an idea with someone and that person copies your idea in a painting, then that person owns copyright in that painting and you do not.
Even if you sell your work or other subject matter, you still own copyright.
Copyright generally lasts the life of the artist plus 70 years ©.