There are several ways to transfer files with SSH.
scp (secure cp) - basic syntax is
scp -r what where.
where are either local files or remote ones. In the latter case, it is in the form
[[user@]host:]file - e.g.
arthur@camelot:path/to/file denotes a file located on computer
camelot into which
scp is supposed to log as user
arthur; if the pathname is relative, it is relative to remote user's
sftp is an interactive FTP-like shell.
tar c files | ssh user@host tar x - pipe a tar archive through ssh connection to
tar spawned on the remote host. Can be reversed (
ssh user@host tar c files | tar x). If you need to transfer just one file, using
cat is also an option (TAR will keep file permissions and modes though).
SSHFS - FUSE-based user mountable file system backed by SSH, which offers seamless integration into the file system hierarchy.
In all cases you have to have the SSH daemon running on at least one of the two machines. To find out hostname use the
hostname utility. You can also use the IP address instead of the hostname - to find that one out use e.g.
ip addr (on Linux, I don't know what is used on Mac OSX, which is of BSD heritage). If you have OpenSSH (which is very likely) check the man pages - they are rather well written.
An alternative (at least on local network) can be e.g. full encrypted NFS (v4+) export, which however is more difficult to set up (might be faster though, unless you use a specially patched version of OpenSSH targeted at HPC).