This tutorial is intentionally short to help you catch up with previous tutorials.
Use the ifconfig(8) command to identify the IP address on 2 Linux PCs connected to the same network.
Use ping(8) on both PCs to check that IP traffic can be routed between these PCs.
Use ps(1) to check whether either or both PCs are running sshd(8), the secure shell server.
If possible use ssh(1) to initiate a remote login and use sftp(1) to transfer files between the 2 computers.
If you can identify a network connected sendmail server, or any other SMTP relay, e.g. qmail, exim, postfix, attempt getting it to relay a test mail message by establishing a telnet connection to port 25 on the server with the mail relay. Most SMTP relays will respond to commands such as HELO, HELP, MAIL From: address, and RCPT To: address. You can send the mail message itself using the DATA command followed by the text of the message, followed by a dot (.) on a line by itself. Use a mail user agent e.g. mail(1) on the machine to which the message was sent to check if it was delivered. MS-Windows also has a telnet command with which you can investigate text-based network services.