[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/BlAeI.png

Please help me how can i add my custom abc.css and filename.js  in magento 2.2.2 .
 
default_header_html.xml file path

app/design/frontend/custom-theme/my-first-theme/Magento_Theme/layout/default_header_html.xml

my css path 

app/design/frontend/custom-theme/my-first-theme/web/css/source/abc.css

my js path
app/design/frontend/custom-theme/my-first-theme/web/js/filename.js