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.