How to update css and JS changes in the Sage 10 theme

I have setup the sage 10 based theme. Now I’m creating the custom AFC block for Gutenberg editor. Blocks are created but when I have write CSS in editor.css and app.css it’s not updating on the block which i have create. Someone can suggest what i can do? Also if want to add external JS for a block how i can add this external JS file.?