How to correctly write the ability to write letters in htaccess?

Question

htaccess

There is a code:

RewriteEngine On
RewriteRule ^r/([0-9]+)$ ./new/new.php?id=$1\&%{QUERY_STRING}

In .htaccess. I don't know him and that's why I'm turning to you. With it, I create a new/new.php file in the store and pages with categories are automatically created by id, it works fine. But I need it not by id, but by login, please reformat this code so that the pages are loaded by login. Thank you very much.