To get your data (files) onto the supercomputer or back to your local machine, there are usually different ways. Sometimes there are computers specifically reserved for this purpose called copy Nodes
Please use these nodes to copy your data to or off the supercomputer, if available, since you will get a better/faster connection and disturb other users less. Also the tools mentioned below might only work on those nodes. If there are no dedicated copy nodes, you can usually use the Log-in Nodes for this purpose.
Secure Copy (scp)
This is generally the easiest way to transfer single files. It builds on ssh usually works on every node (machine) that you can build ssh connection to and can be used like this
$ scp firstname.lastname@example.org:foobar.txt /some/local/directory
this copies the file foobar.txt from the remote machine to your local directory. Turning this around also works:
$ scp foobar.txt email@example.com:/some/remote/directory
and copies the local file to the remote machine. Here you can find some more Examples of SCP syntax.