I want to add one button to the profile page, but I can't find where I can do it, I have entered enough in many classes, but it did not work for me.
Can you show me what I need to do and where exactly?
Sorry for the translator
You shouldn't edit any existing file. Never. The only exception is the config.php file, but really no other file should be edited. Write a plugin instead.
See how it can be done by looking at https://github.com/R-J/kick/blob/master/KickPlugin.php, line 128 & 137 to get a first idea.