Telnet is a protocol allowing you to connect to a remote system and run programs and commands on that system. It is very old and still very much in use today.
Unfortunately, a telnet client sends the user password as clear text, and the connection is not encrypted. On the other hand, a program called ssh exists that can replace both telnet and ftp in a secure, encrypted way.
Ssh stands for Secure Shell. It will encrypt each connection with a random key, so that it is impossible or at least very hard for a third party to decrypt the connection and find the password, or spy on you.
Use putty (Here)