After you have written your article, click the gear in the top-right corner to bring up your article settings. Upload a header image (3000x1500 px) and enter a meta title and entry excerpt. Your header image will also represent your entry NFT when it is minted.
Once you're done, check your meta preview at the bottom of the article settings. This will show you how your article will appear on Mirror, search engines, and social media platforms. This is also a good time to save your article as a draft if you haven’t done so already. Just click Save Draft at the top.