FTP offers many advantages over using your browser's upload feature; namely it is far more reliable and easier to coordinate multiple files at a time.
Server: files.blog-city.com (use IP of files.blog-city.com if using filezilla)
Port: 21000 (not the standard 21)
Username: your email address
Password: your password
You login using the same email and password you use when administering your blog online. You can upload files and photos to all your blogs from the same FTP session. If you log in, but don't see any directory listings, then disconnect and switch your FTP client to PASSIVE mode. Chances are you are behind a firewall.
When you log in you'll be presented with a very simple directory structure. For those of you that have more than one blog, you will see all your blogs listed as directories from your root. Each of those folders contain three folders; /photos/, /MP3s/ and /files/. You can only upload into /photos/, /MP3s/ or /files/ folders. You cannot create any subdirectories anywhere.
When you upload a photo, a thumbnail will automatically be created for you behind the scenes. Only JPG and GIF reside in this folder. If you upload a MP3 file, it will automatically be moved to the /MP3s/ folder. If you upload a non-JPG/GIF/MP3 file, it will automatically be moved to your /files/ folder. The reverse is true; if you upload a JPG/GIF/MP3 to your /files/ folder, it will be automatically moved to its respective folder .
Each time you upload or delete a file, your administration console for that given blog will be updated to reflect the change.
Note; if you are using w.Bloggar, set the initial directory to /yourblogurl/photos/, for example, /myname.blog-city.com/photos/
To find suitable free FTP clients, have a look here