Command not configured for CSS!

I’m a novice. Here because Atom is not exactly easy to work with.
I simply want to use Atom editor to build a simply web site using HTML , CSS and JS with Django as the backend. I also want to be able to simply run it on my browser locally. Nothing fancy. Thus far extremely difficult to do using Atom.

Can someone please assist me.
I able to see my html results. However, the error code: command not configured for CSS!

My css code is not being recognized.