If you haven’t done it yet, I’m going to help you add a header image to your WordPress.org plugin.
The plugin header image dimensions need to be 772px x 250px. You may also want to include a retina-ready high-res image, which would be 1544px x 500px.
In your plugin’s SVN repository, there are a few folders. You need to add your image to the assets folder, with the image names as follows:
To make it even easier for you to add your own header image, I put together a very simple template file. It’s pretty much just set up with the correct 772×250 dimensions and the matching filename.