Hi there,
you can enable the Header as Navigation option in Customizer > Layout > Header.
https://docs.generatepress.com/article/navigation-as-a-header/
This will remove the site header and place the logo inside the Primary Nav.
If that doesn’t work for your needs then please provide a link to your site.
Regarding Images, we don’t store image attachments. You will need to save the image in cloud drive, your WP Media Attachments or use an only image sharing service such as imgur and provide us the link to it.