Home page text boxes

Hi,
I had my website designed for me, and in the home page I have graphic, links to other pages on my website and text in boxes. You can’t see the boxes on the homepage, but where you edit the page the boxes are grey dashes around the text and graphics.

Can someone tell me how to recreate this, so I can add more?
I can’t see where the code ends and begins? I’m not tech savvy.

Thank you
Jenny