Changing the hero image is the most convenient way of customizing your store. At the top of the layout.html file you can find the code shown below. All you have to do is change the link/src attribute accordingly.

<div class="gdp-hero-image">
    <img src="<https://i.gyazo.com/a3b4c6d00c96acb5f0091a62773b2c98.png>" alt="Hero image"/>
</div>