Not pulling in custom files

I'm really sorry for what will be an easy answer but I have everything setup and working, products added and I'm almost ready. I've searched everywhere for an answer to this but to no avail.

Let's say I have to edit the file located at:

/httpdocs/cart/includes/languages/english.php

I'm meant to save it to a custom folder so I save it to:

/httpdocs/cart/includes/languages/custom/english.php

When I check the page webpage nothing has changed. All the help files just say upload to to that custom folder so either:

1. I'm uploading to the wrong place
2. Somewhere there is a file that I'm meant to edit to say there are custom folders

Can anyone help?

You've missed a couple of steps - check here:

https://www.zen-cart.com/tutorials/index.php?article=142

Exactly what I needed to get back on track, many thanks for answering my question (also sorry it's in the wrong forum, just found out what override meant!)