How to change header site name
Go to Settings – General – insert your site name in Site Title form field.
How to upload header
If you have a header logo image, Go to Customize – Header Image – click Add New Image – select an image – click Select and Crop – click Skip cropping (if you don’t need to crop the header image) – click Save and Publish
Recommended header image size is 360px (width) x 160px (height).