Hi, @meda ,
This is Evita from On The Map.
You will need to edit this with CSS and liquid file, if you know coding then it won't tale long, but if you don't have any experience with coding then I suggest you hire a developer for this. And also if you want to edit the checkout page, you have to get the Shopify Plus plan.
You can read more here - https://help.shopify.com/en/themes/development/layouts/checkout