You can write your novel anywhere you want! If you choose to write in the YWP writing space, you’ll see your word count and badges update as you type, plus get access to other fun features, and your novel will be stored on the site. If you choose to write somewhere else (Google docs, your notebook, a series of napkins), then make sure you select the “update my word count manually” option when you create your novel, and visit the site often to update your progress. You can always switch your mind later and edit your choice in “Novel Settings” - just click the wrench to the upper right of the novel's title.