You are probably putting in the username and password we gave you instead of using the username and password you use to log on to your computer. The username we gave you is only to be used in setting the FTP target, and when logging on to your control panel.
If you do not use a password to log on and don't know what your username is, go to Start/Control Panel/ User Accounts and see what name is listed as the username in bold. You should see 'Computer Administrator' below that name. If no password is selected or do not use one, leave that blank on the software.