There are 2 ways to provide username and password when downloading files using wget

Directly as parameters

wget --user "<username-goes-here>" --password "<password-goes-here>" "<file-url-goes-here>"

This has the disadvantage that it will show up in your shell history and in running processes lists, thus exposing your password.

Interactively entering the password

Another way is to tell wget to interactively ask you for the password

wget --user "<username-goes-here>" --ask-password "<file-url-goes-here>"

Here instead of the password showing up in your command, wget asks you to enter your password.