Any person who creates any work (book, play, written or played music, film, photograph, drawing, painting, design etc) automatically owns the copyright. In order to publicise the fact you need to protect it with the copyright symbol (C in a circle, which can be made on your computer by bracketing the capital C), your name and the year. Copyright remains valid for 70 years after the death of the creator of the work, so your descendants wil be able to benefit as well as you can if you wish to licence the use of your work.