you can find luma theme files are located

copy from here

vendor/magento/theme-frontend-luma

add in your theme

app/design/frontend/spacename/theme/

you are missing templates in path /app/design/frontend/Penguin/default/Magento_Theme/templates/html/header.phtml

you can find luma theme files are located

copy from here

vendor/magento/theme-frontend-luma

add in your theme

app/design/frontend/spacename/theme/

you are missing templates in path /app/design/frontend/Penguin/default/Magento_Theme/templates/html/header.phtml

you can find luma theme files are located

copy from here

vendor/magento/theme-frontend-luma

add in your theme

app/design/frontend/spacename/theme/

you can find luma theme files are located

copy from here

vendor/magento/theme-frontend-luma

add in your theme

app/design/frontend/spacename/theme/

you are missing templates in path /app/design/frontend/Penguin/default/Magento_Theme/templates/html/header.phtml