Custom Themes: Where to put images?

Hello Community 

I am embarking on learning how to custom theme SugarCRM and was wondering if anybody out here could help me out with some details.

I have created the CUSTOM less file in my custom directory to override the base CSS

Custom -> themes -> default -> custom.less

and have been able to successfully begin working with the code to change values and so on and so forth. 

I am trying to use images as backgrounds for certain elements and am just not clear on where to upload the images that I would be using for that. 

I created a custom -> themes -> default -> images

Directory and deployed the images there but keep getting notified that my image cannot be loaded. 

background-image: url('images/[image]');

console.log

Failed to load resource: the server responded with a status of 404 (Not Found)

Where does one place these images to have them properly be placed into the cache and be able to be loaded from the cutom.less file?