One-time uploads (Export)
If you wish to upload your images to an FTP server as a one time operation (“upload and forget about them”) then you should export your images. Once the images have been exported there is no further connection between Lightroom and the exported images - your originals remain safe withing Lightroom of course.
Accessing FTP Publisher
To use FTP Publisher to export your images you should:
You will be presented with the FTP Publisher export dialog.
Setting up the destination
To set up the destination FTP server click on the FTP server settings menu and choose Edit... The following window opens to allow you to define your connection.
If this is a server that you'll use frequently then you may save your settings as a preset from the menu at the top of the dialog. Click OK to close the dialog.
Once you have defined your FTP settings you may optionally choose a sub path in which to export your images. This allows you to create a preset with a top level path (perhaps to your user account) that you can reuse frequently, and still be able to upload to different subfolders. The full path is displayed for your convenience.
Other export settings
You should also browse the remaining standard export panels to define how your images will be exported from Lightroom before they are uploaded to the server (eg. the file format, the size, the compression, etc).
Once you're ready press Export and your images will be uploaded to your server.