How to get notified of new chapters of certain mangas?

When you finish reading it there should be 3 options below the paragraph that says you've come to the end. The 3 options should say:
want to read
Reading
Already read
Then you click the reading one if you're still reading it/its still ongoing/incompete
The already read if you finished
And want to read if you...want to read it.

I hope this wasnt to confusing ╥﹏╥

To add to this, if you choose reading or already read, you automatically get notifications.