Where to find query for users in admin

Hello, i’m tinkering with wp, and i am very frustrated where to find the query that looks for the username or password in a database in wp-login.php. i would like to create my own login form for users and i do not like to use a plugin i would like to hard code it. i already have it running. what i need is someone to pinpoint where the exact location of those queries might be hiding?? or maybe i found it but i didn’t know it was that. Or how does the login system verifies the login inputs what does it searches for thanks.