UNIX for Dummies Questions & Answers

Hello all,
I am new to Linux here..am doing my 1st year engineering with majors in computer software. This is the first time I am encountering a UNIX system in school to work practically. I was just through the basec Linux Terminal commands of creating new file, editing, shell programs etc.
In my school the UNIX lab goes like this..Redhat Fedora linux distribution is installed standalone in one computer..and ther other computers are networked to it. Say 9 computers run Windows and the 10th one runs Redhat. The 10th one acts as the server as per the information given by my professor. Students work on the other 9 computer with WIndows...and Prof works with the 10th. Generally we are instructed to go to Run> and type "telnet 10.1.2.150" ..after pressing enter, a new black window opens where we type in the Username and password to login to the UNix server. The point is all the other 9 computers use the same username and password for logging in to the unix server. There is a separate directory named "pmrcse" for our department within which we create our files, and other things using unix commands. All these runs within that telnet window. When I type the "who" command, I see the following:
root pts/0 Apr 23 10:43 (:0)
root pts/1 May 6 18:19 (:0.0)
pmrcse pts/3 May 6 18:20 (10.1.2.21)
pmrcse pts/5 May 6 18:23 (10.1.2.10)
pmrcse pts/7 May 6 18:34 (10.1.2.11)
pmrcse pts/9 May 6 18:21 (10.1.2.4)

From this I guess that 4 computers out of the other 9 windows systems have connected to the Unix server thru telnet.
My system is the one with the IP 10.1.2.11 pts/7
""Now if I want to chat with the other system , say pts/9 using the "talk" command or "write" command.. How do I do that?""
I tried entering "talk pmrcse@10.1.2.4" ..but its wasnt fruitful..Is there any feature that need to be enabled in the Redhat system for using the "talk" command?

Thanks in advance!