It is very important to backup any files you do not want to lose. Your computer could crash at any time and you could lose everything on it.
You can backup in a number of ways.
Acquire an external disk drive and use it regularly. But remember that this too can fail!
Use a memory stick - but these are readily lost or mislaid, and can also fail!
Purchase storage space online from one of the providers of such a service - a web search for 'online storage' produces a large number of such providers.
Email important documents to yourself, or to a friend or relative. Split the document into sections if necessary.
Use the DS-Filestore storage facility at https://dsfiles.ds.cam.ac.uk. Instructions can be found at http://www.ucs.cam.ac.uk/desktop-services/ds-filestore/access.
The big advantage of 3, 4, and 5 is that the backup is separate from your own computers and other belongings, and therefore available in the event of a disaster such as theft, fire or flood. On the other hand the storage provided is limited, and it is not possible, for example, to save large numbers of photographs in this way. These are best limited to the various documents you create for your academic work.