Header Media is another popular section in the Customizer sidebar. That being said, this is not a section that's available in the current default theme, Twenty Nineteen. However, I'm describing it here since you're likely to find it in many other themes. To demonstrate this, I'll switch to the previous default theme of WordPress, Twenty Seventeen. This is what the Header Media section looks like when using that theme. Refer to the following screenshot:
Most themes will allow you to select any image to be placed inside the header, and sometimes even a video, as Twenty Seventeen does. Twenty Seventeen also has some specific requirements for the header image (actually, most themes have, and Twenty Seventeen is only an example of that). The suggested size is 2,000 pixels wide by 1,200 pixels tall, but you don't have to worry all that much about this because WordPress also provides some handy image editing tools. All you have to do here is use the Choose image or Add new image buttons and select one of the pictures from your Media Library, or upload a new one. WordPress will immediately redirect you to the aforementioned image editing tools, where you can adjust and crop your image, as shown in the following screenshot:
After clicking on the Crop Image button and then Save & Publish, we're done with setting up the header image. Here's what the site might look like afterward:
