WordPress gives you several draft options so that you can save your work without having to publish it immediately.
This way you can work on a new post/page as much as you want and publish it only when it is ready.
To save a post as a draft, go to your blog's admin area > Posts > Add New. Write your post and when you wish to save your progress, click the Save Draft button.
To save a page as a draft, go to your blog's admin area > Pages > Add New. Enter the content of the new page and click the Save Draft button to save your page as a draft.
If you want to see a video tutorial on how to save a post/page as a draft in WordPress, click Play Video on the screen below.
Find more useful WordPress videos at WordPress.tv.