Xamarin Editor

I have a social network source code with Xamarin. I want to edit it.
My source developed by Xamarin language.
In my app, when my user wants to share a video outside of my app, I want my watermark and client username written, and at the end of a few seconds the profile photo, username and logo of my app.
Similar to the Similar to the TikTac app:

Deadline:3 days, Max Budget : 80NZD
Apply with 3days, 80NZD”