How to add xml to fire tv

Please excuse me if this sounds dumb to you but how do you add advancedsettings.xml to fire tv.

I have installed a new version of kodi (my last install – not done by me! – was a banned version) but am having bufferring issues. My connection is only to a NAS, no-where else.
I read on hear about creating an advancedsettings.xml which hopefully will fix the issue.

I’ve created the file and have it on a usb stick in the back of the fire tv.
I’ve gone into es file but I cannot figure how to copy the file from the usb to the fire tv.

help would be more than appreciated. Thanks