Hi Louise,
To upload your tree to ancestry, you need to save it as a GEDCOM file. This is an export option in FTM. However, when you do this, it will NOT upload any photos, files etc. You will need to add these manually.
To back up your files to a disk or memory stick, you just need to find the data file you are using (will end in .ftm) and save that file to your storage device.
Cheers,
Michelle