How can find other username and password of facebook?

[pri✍]

Hacking people's account is like robbing his/her bank's account, it's criminal.
What on earth you want to do that? become identity robber? you think that's cool?

Username on the contrary is legal as it's a unique name of a person which might have the same name but not same username.
If your FB address is https://www.facebook.com/cheers.to, which is shown in the About or in your URL, then your username is "cheers.to".