Newly created website does not have the logo yet, the website title is shown in the top left corner instead of the logo.
Once you have the logo designed for your business, you should go to Settings page of Admin section and upload your logo* on the "Site identity" tab.
* in Classic and Blue themes the logo will preserve its original size, while in Modern theme it will be automatically resized to fit the layout.
The logo for coupon can be different from the website logo or if you want to have the same logo on both – coupon and site – you should upload same picture to both fields.
Here is how the logo will look like in Classic theme: