While in the creation process, if you tap the "<" or "x" you'll see a prompt asking if you want to save a draft or discard the post. Tapping "save" will create a draft of your post which you can resume editing by tapping on the draft from the Inspiration feed (lightbulb icon). 


Drafts can be found at the top of the Inspiration feed (lightbulb icon) on the home screen.