When you use ftp, you access your host account at its root, at its main directory. When you use an online file manager, you interface with your hosting account through a web page. When you use an ftp program, you interface directly with the server. You need ftp software because it works best with an ftp server. Don’t worry. Most ftp software is shareware and really easy to use. With ftp, you can drag and drop files into your account instead of having to let an online file manager "browse" your hard drive. A lot of adult webmasters prefer ftp. When you buy your own web space you’ll have to use ftp because that’s the way it’s done with paid hosting.