How to properly create a user in Ubuntu?

Question

ubuntu

Hello. In general, this is the task. Ubuntu OS installed. How to create another user correctly so that he is not root, but can run programs on his behalf in the terminal.
I created a user, but when I go to it in the terminal
su - another_user
, the application does not start from under it (I'm trying to start Visual Studio Code).
I set the rights for the new user to access the var/www directory, so I want VS Code to work from under it.
Maybe something is not configured somewhere?
PS By the way, from the initial screen I also can not get into a new user - after entering the password for ten seconds, a black screen, and then again the initial screen.