If you want to automate the publishing process, so that you do not have to enter your username and password every time you want to publish, then you can include this information in your Publishing settings.

Note that if you have a group blog, only an Administrator can adjust these settings. Members of your group blog are not able to access or modify the FTP settings that are recorded here.
You already entered your FTP Server and other information when you created your blog originally. You can choose to change that information here if you want.