See the page on generating keys.
Files can be transferred with scp, which is more or less a cp equivalent, but then to or from a remote machine.
For example, to copy the (local) file localfile.txt to your home directory on the cluster (where <vsc-loginnode> is a loginnode), use:
scp localfile.txt <vsc-account>@<vsc-loginnode>:
Likewise, to copy the remote file remotefile.txt from your home directory on the cluster to your local computer, use:
scp <vsc-account>@<vsc-loginnode>:localfile.txt .
The colon is required!
The sftp is an equivalent of the ftp command, but it uses the secure ssh protocol to connect to the clusters.
One easy way of starting a sftp session is