Images
In the editor, choose Upload image, pick a file, and add a short description in Alternative text. Then upload and insert it.
OnceMarked resizes and compresses uploads for you. Choose a smaller maximum size for quicker loading, or a larger one for more detail. Pro unlocks larger sizes and the quality control under Advanced. Images aren't enlarged.
Use Image library to reuse something you've already uploaded. Storage is shared across your account's blogs; your allowance is shown in the dashboard.
You can also link to an image hosted elsewhere in Markdown:
External images don't use your upload allowance, but their availability depends on the other website. Deleting an uploaded image can break posts that use it.