Sections are the main base block of building anything. Sections contain all other elements inside them. A section needs to be added first to make any design.
Here is how you can add a new section:
If you create a new page on your site, you will see the option to add a new section automatically,
Here is what it should look like:
If a page already has sections, here is how you can add a new section.
Refer to the GIF below: