Image bannern page

I am very new to F7 and downloaded V2. How can you add a image as a header image to the framework I did the img src and nothing works do I need to store it in the image folder?
the image will not be downloaded or nothing it will be a image banner like you see on some websites but just on a app.
Thank You for the Help

What is header image? It is better to show what you have tried first