You can add a header image to make you blog more attractive.
NB different themes may work differently. For example they need different sized images.
Accessing the Header Editor
Either :
On your blog’s dashboard, got to Appearance-> Header
or choose Customize from the blog Admin bar
Header Section of The Customiser
Note that you are told the size of image that is needed [1].
Click Add new image. [2].
Choose an Image
The Media Library Will open, you can choose an exiting image if any or Select Files from your computer[1].
Pick a file from your computer [2]
The image will upload and selected. Choose Select and Crop [3].
Crop Image
Next you will crop the image. The selection will be at the correct aspect ratio, it is best just to move this and then click Crop Image[1].
Preview and Save
The Crop image dialog will close and you will be able to preview your header. If you are happy Click Save & Publish and then close the customiser.