I don’t want to make a permanent change. All I want is to create a different color background for several paragraphs within a post. For instance, if I want a different background color only for a quote within a post, how would I do that? What code would I use?
We cannot edit the underlying code in our templates at wordpress.com. Perhaps the only way you could affect such a change is to purchase a css customization upgrade but that’s not really as “temporary” as you are indicating for a single post.
The work around you can use that I’ve tried is to create an image in a program like msPaint and place the text overtop of the background colour you choose. Then you can upload it into the post as an image.