How to Verify Website Using Upload File Method
This quick guide will show you how to upload any verification file to verify that you own the domain. This can be used with Google Webmaster, Bing Webmaster or any of the social media websites that require you to upload a file to verify you own the domain.
First, login to your store and go to Settings-->Store Settings-->Tags, Keys and Codes.
Paste your code in the Header box. If you have a txt file you want to upload, do it under the last box labeled - Ads.txt File Content.