Write short things. Ask yourself how they could be better. Eeven stences can be great or not so. Work on tiny stories a few lines long. Play with words. At the same time you can start reading up on the subject and seeing what else is involved: grammar, punctuation, style.... Later of course, there can be business. Work up to novels, if that's where you want to go. Look into planning, endless you just want to start writing and see where it goes, you generate a lot of notes, research etc.