Assets

You can simply put your assets where you want in the sources directory and add your assets directories in settings.FILES_TO_SYNC, they will be copied to your build directory.

But with Optimus this is only required for real static assets like images or fonts. For CSS and Javascript you should manage them with webassets that is already installed with Optimus.

With webassets you manage your assets as packages named Bundle, like a bundle for your main CSS, another for your IE CSS hacks/patchs and another for your Javascripts files. You will have to register your custom bundles in settings.BUNDLES and enable them in settings.ENABLED_BUNDLES.

The benefit of webassets is that it can pre and post process all your assets. This is usually used to minify and pack multiple files in one final file. Read the webassets documentation for more details how to use this and to manage bundle assets in your templates.