If you have recently moved to Ubuntu and don't know how to FTP, there are some free and easy solutions to this.
If you know how to install software from the synaptic package manager, you are going to be able to get a free program that will let you FTP.
Load up the package manager and look for Filezilla.
Check and apply it to be installed.
Wait for the download and installation and now you have a free FTP program.
Under Applications then Internet you should see a big red icon with the name Filezilla.
Click on that to start the program.
Once started you need to add a new site.
Click on File and Site Manager or hit Control+S to set up a new site.
When this box comes up, click on new site, fill in your details, and click OK.
Now you can double click on the site name to connect to that server via FTP.
You will notice a few boxes in the Filezilla program.
At the top is your connection information.
This gives you an idea of if you connected successfully or why you might have been denied access or been logged out.
On the left side of the screen are file folders that are on your computer.
To the right are file folders of your server.
If you drag and drop files from the left or the right you can upload and download files from your computer to the server both ways.
Just use it like a normal file system like you would on your computer or a backup drive.
On the bottom of the screen gives you details about what is being uploaded and downloaded and how fast that these connections are going.
For the most part advanced features are pretty easy to figure out, but these are the basics of what you will actually need.