Contracted writers can upload their own series cover directly. You must own or have the rights to use every image, artwork, font and other element in the cover, and it must not include third-party logos or trademarks. 
To upload a cover:

• Open your series.

• Tap Edit Cover.

• Upload your cover image.

• The image will be reviewed and will go live automatically once approved.

Before uploading, make sure that:

• The cover image is square (1:1) and at least 1,000 × 1,000 pixels.

• The cover image is under 5 MB.

• The series title is clearly visible.