Changing Page Headers to an Image

[fitnesslife]

Hi! I would like to change the header of my blog posts page to an image that I would like to be using. For example, this photo below illustrates what I'd like to achieve.

I would also love to do this for my about page as well, since the page will be very bland otherwise.

Thanks in advance!

[fitnesslife]

Adding something like to my product page would help as well.

[fitnesslife]

- Bump -

[fitnesslife]

- Bump -