How to Resize Header Image Dimensions in Coraline Theme?

Hi,

I am trying to change my header image from the default 990×180 to 990×140 in the Coraline theme, but to no avail.

Here is my website url: https://www.brighamyen.com

I would like to change the header image to this:

https://brighamyen.com/wp-content/uploads/2011/07/brigham-yen-header-image.jpg

Can anyone help me?

Thanks so much in advance.

BY