Color Background help

Site URL: https://wisteria-violin-nbre.squarespace.com/subscription

Hello, 

I'm having issues on how to add color background to sections of my page. 

One solution I tried is by making it a index page, and adding a color of the background as a media. The problem with this is that the color takes over that whole section. Is there a code to add space and a border around it?

The second thing I tried was adding the color background code to specific blocks, but because some of them are next to each other the color doesn't line up.

Does anyone know or have a code that would allow me do add color to multiple blocks, without creating an index page, and keeping my border?

I would really appreciate your help. Thank you.

Hi,
What is the password of your website?

Best,
Leopold