Deepak BuddyBoss

@patrick for CSS changes you should add them to /css/custom.css
If you need to edit a specific php file you should copy it from the main theme and edit the files in the same subdirectory in the child theme, if the directory does not exist you will need to create ie.
If you are adding functionality without needing to edit actual files you can use the /buddyboss-child-inc/child-theme.php