You can't log in with a username and your ftp password. The ftp password is for use with ftp software, you could download something like click here and connect via ftp if you wish.
To log in and use the control panel, you need to use your username, typically an email address and the password relevant to that. This will have been emailed to you when you opened the account. If you have forgotten/lost the password, there is a forgotten password link on the log in page.