Secure authentication system in python?
It's hard to be specific without knowing your setup. However, the one thing you should not do is reinventing the wheel. Security is tricky, if your wheel is lacking something you may not know until it's too late.
I wouldn't be surprised if your web framework came with a module/library/plugin for handling users, logins and sessions. Read its documentation and use it: it was hopefully written by people who know a bit about security.
If you want to know how it's done, study the documentation and source of said module.
I am making a web application in python and I would like to have a secure login system.
I have done login systems many times before by having the user login and then a random string is saved in a cookie which is also saved next to that user in a database which worked fine but it was not very secure.
I believe understand the principles of an advanced system like this but not the specifics:

Use HTTPS for the login page and important pages
Hash the password saved in the database(bcrypt, sha256? use salt?)
Use nonces(encrypted with the page url and ip?)

But apart from those I have no idea how to reliably check if the person logged in is really the user, or how to keep sessions between page requests and multiple open pages securely, etc.
Can I have some directions (preferably specific ones since I am new to this advanced security programming.
I am just trying to accomplish a basic user login-logout to one domain with security, nothing too complicated.