FTP is just File Transfer Protocol, a program used in the early days for editing websites.
Download Filezilla, a free FTP program, or use the version in the VU+ Control Centre.
http://www.vuplus-community.net/board/threads/filezilla.2514/
http://www.vuplus-community.net/board/threads/vucc-vu-control-centre-v0-8.4589/
Once downloaded, and running, you just connect to your receiver, by filling in the relevant information:
Host - This is your receivers IP Address, you can find this by going into your receivers menu, finding Network and clicking on the Adapter settings.
Username - root
Password - leave blank, unless you've set up a password
Port - also leave blank
Now click on the Quick Connect button and you should see the folders, from your receiver, on the right and your PC's folders on the left.
Personally i would use dreamboxedit, to back up your channels, and bouquets, this program also allows you to edit you channel list.
http://www.vuplus-community.net/board/threads/dreamboxedit.18975/
Like Filezilla this is very easy to use, once you've set up the basics.
First set up a new folder, called settings, on your computer desktop, by right clicking and selecting the new folder option, this is where your channel list is saved.
Next start up dreamboxedit, click on Tools, and options.
Like Filezilla enter your receivers ip address, in the IP address box, root in username, and click save.
Now click on File and fast FTP download, all your channels, and bouquets, on your VU+ should now be displayed, and saved.