Cannot find custom fields in vendors panel

Replies: 0

I need to have a custom fields in vendor’s product page.
Using the code below I see the new tab but don’t know where to find this in the product pages (I want to write some text inside, depends on the product features).
I’d like to solve this without a plugin.
See imgs url below. Is this idea possible?
2 screenshot here:
https://i.stack.imgur.com/PgGNy.png
https://i.stack.imgur.com/WPIcu.png
Thank’s