When you're creating an advert, you can edit each section by selecting the relevant link. The page will update and show the editing screen for the section you've chosen. Changes aren't saved automatically, so once you've updated what you need, select the blue button at the bottom of the page.
When you select the button, your progress will be saved, and you'll be taken back to the advert's main page.
If you select 'Back to advert' in the top-left corner, anything you've added to the advert won't be saved.
Your advert will stay as a draft until you've paid for it. After paying, your advert will go live.
Good to know: Your draft advert will last for 28 days from when you started it. After that time, it'll be deleted and you'll need to start again.